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HandlerThread应用(对比AsyncTask)

之前说过HandlerThread的原理::

Handler机制的分发中心就在Looper中的loop(),HandlerThread将loop转到子线程中处理,降低了主线程的压力,使主界面更流畅

   其实说白了,创建HandlerThread,只是为了用此线程的looper  最终的runnable都还是post到主线程运行(已用Toast测试过)

最终的最终就是降低了Loop中的loop功耗,依旧在主线程中运行。


这里我以Launcher2的代码来说说HandlerThread的具体应用::


/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.launcher2;

import android.app.SearchManager;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProviderInfo;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.ContentProviderClient;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.content.Intent.ShortcutIconResource;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Environment;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Parcelable;
import android.os.Process;
import android.os.RemoteException;
import android.os.SystemClock;
import android.util.Log;

import com.android.launcher.R;
import com.android.launcher2.InstallWidgetReceiver.WidgetMimeTypeHandlerData;

import java.lang.ref.WeakReference;
import java.net.URISyntaxException;
import java.text.Collator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;

/**
 * Maintains in-memory state of the Launcher. It is expected that there should be only one
 * LauncherModel object held in a static. Also provide APIs for updating the database state
 * for the Launcher.
 */
public class LauncherModel extends BroadcastReceiver {
    static final boolean DEBUG_LOADERS = false;
    static final String TAG = "Launcher.Model";

    private static final int ITEMS_CHUNK = 6; // batch size for the workspace icons
    private final boolean mAppsCanBeOnExternalStorage;
    private int mBatchSize; // 0 is all apps at once
    private int mAllAppsLoadDelay; // milliseconds between batches

    private final LauncherApplication mApp;
    private final Object mLock = new Object();
    private DeferredHandler mHandler = new DeferredHandler();
    private LoaderTask mLoaderTask;

    // Handler机制的分发中心就在Looper中的loop(),HandlerThread将loop转到子线程中处理,降低了主线程的压力,使主界面更流畅
    private static final HandlerThread sWorkerThread = new HandlerThread("launcher-loader");
    static {
        sWorkerThread.start();
    }
    private static final Handler sWorker = new Handler(sWorkerThread.getLooper());

    // We start off with everything not loaded.  After that, we assume that
    // our monitoring of the package manager provides all updates and we never
    // need to do a requery.  These are only ever touched from the loader thread.
    private boolean mWorkspaceLoaded;
    private boolean mAllAppsLoaded;

    private WeakReference<Callbacks> mCallbacks;

    // < only access in worker thread >
    private AllAppsList mAllAppsList;

    // sItemsIdMap maps *all* the ItemInfos (shortcuts, folders, and widgets) created by
    // LauncherModel to their ids
    static final HashMap<Long, ItemInfo> sItemsIdMap = new HashMap<Long, ItemInfo>();

    // sItems is passed to bindItems, which expects a list of all folders and shortcuts created by
    //       LauncherModel that are directly on the home screen (however, no widgets or shortcuts
    //       within folders).
    static final ArrayList<ItemInfo> sWorkspaceItems = new ArrayList<ItemInfo>();

    // sAppWidgets is all LauncherAppWidgetInfo created by LauncherModel. Passed to bindAppWidget()
    static final ArrayList<LauncherAppWidgetInfo> sAppWidgets =
        new ArrayList<LauncherAppWidgetInfo>();

    // sFolders is all FolderInfos created by LauncherModel. Passed to bindFolders()
    static final HashMap<Long, FolderInfo> sFolders = new HashMap<Long, FolderInfo>();

    // sDbIconCache is the set of ItemInfos that need to have their icons updated in the database
    static final HashMap<Object, byte[]> sDbIconCache = new HashMap<Object, byte[]>();

    // </ only access in worker thread >

    private IconCache mIconCache;
    private Bitmap mDefaultIcon;

    private static int mCellCountX;
    private static int mCellCountY;

    protected int mPreviousConfigMcc;

    public interface Callbacks {
        public boolean setLoadOnResume();
        public int getCurrentWorkspaceScreen();
        public void startBinding();
        public void bindItems(ArrayList<ItemInfo> shortcuts, int start, int end);
        public void bindFolders(HashMap<Long,FolderInfo> folders);
        public void finishBindingItems();
        public void bindAppWidget(LauncherAppWidgetInfo info);
        public void bindAllApplications(ArrayList<ApplicationInfo> apps);
        public void bindAppsAdded(ArrayList<ApplicationInfo> apps);
        public void bindAppsUpdated(ArrayList<ApplicationInfo> apps);
        public void bindAppsRemoved(ArrayList<ApplicationInfo> apps, boolean permanent);
        public void bindPackagesUpdated();
        public boolean isAllAppsVisible();
        public void bindSearchablesChanged();
    }

    LauncherModel(LauncherApplication app, IconCache iconCache) {
        mAppsCanBeOnExternalStorage = !Environment.isExternalStorageEmulated();
        mApp = app;
        mAllAppsList = new AllAppsList(iconCache);
        mIconCache = iconCache;

        mDefaultIcon = Utilities.createIconBitmap(
        		// 默认图片
                mIconCache.getFullResDefaultActivityIcon(), app);

        final Resources res = app.getResources();
        // 延时load
        mAllAppsLoadDelay = res.getInteger(R.integer.config_allAppsBatchLoadDelay);
        // batchSize
        mBatchSize = res.getInteger(R.integer.config_allAppsBatchSize);
        // 设备配置 
        Configuration config = res.getConfiguration();
        mPreviousConfigMcc = config.mcc;
    }

    public Bitmap getFallbackIcon() {
        return Bitmap.createBitmap(mDefaultIcon);
    }

    public void unbindWorkspaceItems() {
        sWorker.post(new Runnable() {
            @Override
            public void run() {
                unbindWorkspaceItemsOnMainThread();
            }
        });
    }

    /** Unbinds all the sWorkspaceItems on the main thread, and return a copy of sWorkspaceItems
     * that is save to reference from the main thread. */
    private ArrayList<ItemInfo> unbindWorkspaceItemsOnMainThread() {
        // Ensure that we don't use the same workspace items data structure on the main thread
        // by making a copy of workspace items first.
        final ArrayList<ItemInfo> workspaceItems = new ArrayList<ItemInfo>(sWorkspaceItems);
        mHandler.post(new Runnable() {
            @Override
            public void run() {
               for (ItemInfo item : workspaceItems) {
                   item.unbind();
               }
            }
        });

        return workspaceItems;
    }

    /**
     * Adds an item to the DB if it was not created previously, or move it to a new
     * <container, screen, cellX, cellY>
     */
    static void addOrMoveItemInDatabase(Context context, ItemInfo item, long container,
            int screen, int cellX, int cellY) {
        if (item.container == ItemInfo.NO_ID) {
            // From all apps
            addItemToDatabase(context, item, container, screen, cellX, cellY, false);
        } else {
            // From somewhere else
            moveItemInDatabase(context, item, container, screen, cellX, cellY);
        }
    }

    static void updateItemInDatabaseHelper(Context context, final ContentValues values,
            final ItemInfo item, final String callingFunction) {
        final long itemId = item.id;
        final Uri uri = LauncherSettings.Favorites.getContentUri(itemId, false);
        final ContentResolver cr = context.getContentResolver();

        Runnable r = new Runnable() {
            public void run() {
                cr.update(uri, values, null, null);

                ItemInfo modelItem = sItemsIdMap.get(itemId);
                if (item != modelItem) {
                    // the modelItem needs to match up perfectly with item if our model is to be
                    // consistent with the database-- for now, just require modelItem == item
                    String msg = "item: " + ((item != null) ? item.toString() : "null") +
                        "modelItem: " + ((modelItem != null) ? modelItem.toString() : "null") +
                        "Error: ItemInfo passed to " + callingFunction + " doesn't match original";
                    throw new RuntimeException(msg);
                }

                // Items are added/removed from the corresponding FolderInfo elsewhere, such
                // as in Workspace.onDrop. Here, we just add/remove them from the list of items
                // that are on the desktop, as appropriate
                if (modelItem.container == LauncherSettings.Favorites.CONTAINER_DESKTOP ||
                        modelItem.container == LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
                    if (!sWorkspaceItems.contains(modelItem)) {
                        sWorkspaceItems.add(modelItem);
                    }
                } else {
                    sWorkspaceItems.remove(modelItem);
                }
            }
        };

        if (sWorkerThread.getThreadId() == Process.myTid()) {
            r.run();
        } else {
            sWorker.post(r);
        }
    }
    /**
     * Move an item in the DB to a new <container, screen, cellX, cellY>
     */
    static void moveItemInDatabase(Context context, final ItemInfo item, final long container,
            final int screen, final int cellX, final int cellY) {
        item.container = container;
        item.cellX = cellX;
        item.cellY = cellY;

        // We store hotseat items in canonical form which is this orientation invariant position
        // in the hotseat
        if (context instanceof Launcher && screen < 0 &&
                container == LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
            item.screen = ((Launcher) context).getHotseat().getOrderInHotseat(cellX, cellY);
        } else {
            item.screen = screen;
        }

        final ContentValues values = new ContentValues();
        values.put(LauncherSettings.Favorites.CONTAINER, item.container);
        values.put(LauncherSettings.Favorites.CELLX, item.cellX);
        values.put(LauncherSettings.Favorites.CELLY, item.cellY);
        values.put(LauncherSettings.Favorites.SCREEN, item.screen);

        updateItemInDatabaseHelper(context, values, item, "moveItemInDatabase");
    }

    /**
     * Resize an item in the DB to a new <spanX, spanY, cellX, cellY>
     */
    static void resizeItemInDatabase(Context context, final ItemInfo item, final int cellX,
            final int cellY, final int spanX, final int spanY) {
        item.spanX = spanX;
        item.spanY = spanY;
        item.cellX = cellX;
        item.cellY = cellY;

        final ContentValues values = new ContentValues();
        values.put(LauncherSettings.Favorites.CONTAINER, item.container);
        values.put(LauncherSettings.Favorites.SPANX, spanX);
        values.put(LauncherSettings.Favorites.SPANY, spanY);
        values.put(LauncherSettings.Favorites.CELLX, cellX);
        values.put(LauncherSettings.Favorites.CELLY, cellY);
        updateItemInDatabaseHelper(context, values, item, "resizeItemInDatabase");
    }


    /**
     * Update an item to the database in a specified container.
     */
    static void updateItemInDatabase(Context context, final ItemInfo item) {
        final ContentValues values = new ContentValues();
        item.onAddToDatabase(values);
        item.updateValuesWithCoordinates(values, item.cellX, item.cellY);
        updateItemInDatabaseHelper(context, values, item, "updateItemInDatabase");
    }

    /**
     * Returns true if the shortcuts already exists in the database.
     * we identify a shortcut by its title and intent.
     */
    static boolean shortcutExists(Context context, String title, Intent intent) {
        final ContentResolver cr = context.getContentResolver();
        Cursor c = cr.query(LauncherSettings.Favorites.CONTENT_URI,
            new String[] { "title", "intent" }, "title=? and intent=?",
            new String[] { title, intent.toUri(0) }, null);
        boolean result = false;
        try {
            result = c.moveToFirst();
        } finally {
            c.close();
        }
        return result;
    }

    /**
     * Returns an ItemInfo array containing all the items in the LauncherModel.
     * The ItemInfo.id is not set through this function.
     */
    static ArrayList<ItemInfo> getItemsInLocalCoordinates(Context context) {
        ArrayList<ItemInfo> items = new ArrayList<ItemInfo>();
        final ContentResolver cr = context.getContentResolver();
        Cursor c = cr.query(LauncherSettings.Favorites.CONTENT_URI, new String[] {
                LauncherSettings.Favorites.ITEM_TYPE, LauncherSettings.Favorites.CONTAINER,
                LauncherSettings.Favorites.SCREEN, LauncherSettings.Favorites.CELLX, LauncherSettings.Favorites.CELLY,
                LauncherSettings.Favorites.SPANX, LauncherSettings.Favorites.SPANY }, null, null, null);

        final int itemTypeIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.ITEM_TYPE);
        final int containerIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.CONTAINER);
        final int screenIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.SCREEN);
        final int cellXIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.CELLX);
        final int cellYIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.CELLY);
        final int spanXIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.SPANX);
        final int spanYIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.SPANY);

        try {
            while (c.moveToNext()) {
                ItemInfo item = new ItemInfo();
                item.cellX = c.getInt(cellXIndex);
                item.cellY = c.getInt(cellYIndex);
                item.spanX = c.getInt(spanXIndex);
                item.spanY = c.getInt(spanYIndex);
                item.container = c.getInt(containerIndex);
                item.itemType = c.getInt(itemTypeIndex);
                item.screen = c.getInt(screenIndex);

                items.add(item);
            }
        } catch (Exception e) {
            items.clear();
        } finally {
            c.close();
        }

        return items;
    }

    /**
     * Find a folder in the db, creating the FolderInfo if necessary, and adding it to folderList.
     */
    FolderInfo getFolderById(Context context, HashMap<Long,FolderInfo> folderList, long id) {
        final ContentResolver cr = context.getContentResolver();
        Cursor c = cr.query(LauncherSettings.Favorites.CONTENT_URI, null,
                "_id=? and (itemType=? or itemType=?)",
                new String[] { String.valueOf(id),
                        String.valueOf(LauncherSettings.Favorites.ITEM_TYPE_FOLDER)}, null);

        try {
            if (c.moveToFirst()) {
                final int itemTypeIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.ITEM_TYPE);
                final int titleIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.TITLE);
                final int containerIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.CONTAINER);
                final int screenIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.SCREEN);
                final int cellXIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.CELLX);
                final int cellYIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.CELLY);

                FolderInfo folderInfo = null;
                switch (c.getInt(itemTypeIndex)) {
                    case LauncherSettings.Favorites.ITEM_TYPE_FOLDER:
                        folderInfo = findOrMakeFolder(folderList, id);
                        break;
                }

                folderInfo.title = c.getString(titleIndex);
                folderInfo.id = id;
                folderInfo.container = c.getInt(containerIndex);
                folderInfo.screen = c.getInt(screenIndex);
                folderInfo.cellX = c.getInt(cellXIndex);
                folderInfo.cellY = c.getInt(cellYIndex);

                return folderInfo;
            }
        } finally {
            c.close();
        }

        return null;
    }

    /**
     * Add an item to the database in a specified container. Sets the container, screen, cellX and
     * cellY fields of the item. Also assigns an ID to the item.
     */
    static void addItemToDatabase(Context context, final ItemInfo item, final long container,
            final int screen, final int cellX, final int cellY, final boolean notify) {
        item.container = container;
        item.cellX = cellX;
        item.cellY = cellY;
        // We store hotseat items in canonical form which is this orientation invariant position
        // in the hotseat
        if (context instanceof Launcher && screen < 0 &&
                container == LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
            item.screen = ((Launcher) context).getHotseat().getOrderInHotseat(cellX, cellY);
        } else {
            item.screen = screen;
        }

        final ContentValues values = new ContentValues();
        final ContentResolver cr = context.getContentResolver();
        item.onAddToDatabase(values);

        LauncherApplication app = (LauncherApplication) context.getApplicationContext();
        item.id = app.getLauncherProvider().generateNewId();
        values.put(LauncherSettings.Favorites._ID, item.id);
        item.updateValuesWithCoordinates(values, item.cellX, item.cellY);

        Runnable r = new Runnable() {
            public void run() {
                cr.insert(notify ? LauncherSettings.Favorites.CONTENT_URI :
                        LauncherSettings.Favorites.CONTENT_URI_NO_NOTIFICATION, values);

                if (sItemsIdMap.containsKey(item.id)) {
                    // we should not be adding new items in the db with the same id
                    throw new RuntimeException("Error: ItemInfo id (" + item.id + ") passed to " +
                        "addItemToDatabase already exists." + item.toString());
                }
                sItemsIdMap.put(item.id, item);
                switch (item.itemType) {
                    case LauncherSettings.Favorites.ITEM_TYPE_FOLDER:
                        sFolders.put(item.id, (FolderInfo) item);
                        // Fall through
                    case LauncherSettings.Favorites.ITEM_TYPE_APPLICATION:
                    case LauncherSettings.Favorites.ITEM_TYPE_SHORTCUT:
                        if (item.container == LauncherSettings.Favorites.CONTAINER_DESKTOP ||
                                item.container == LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
                            sWorkspaceItems.add(item);
                        }
                        break;
                    case LauncherSettings.Favorites.ITEM_TYPE_APPWIDGET:
                        sAppWidgets.add((LauncherAppWidgetInfo) item);
                        break;
                }
            }
        };

        if (sWorkerThread.getThreadId() == Process.myTid()) {
            r.run();
        } else {
            sWorker.post(r);
        }
    }

    /**
     * Creates a new unique child id, for a given cell span across all layouts.
     */
    static int getCellLayoutChildId(
            long container, int screen, int localCellX, int localCellY, int spanX, int spanY) {
        return (((int) container & 0xFF) << 24)
                | (screen & 0xFF) << 16 | (localCellX & 0xFF) << 8 | (localCellY & 0xFF);
    }

    static int getCellCountX() {
        return mCellCountX;
    }

    static int getCellCountY() {
        return mCellCountY;
    }

    /**
     * Updates the model orientation helper to take into account the current layout dimensions
     * when performing local/canonical coordinate transformations.
     */
    static void updateWorkspaceLayoutCells(int shortAxisCellCount, int longAxisCellCount) {
        mCellCountX = shortAxisCellCount;
        mCellCountY = longAxisCellCount;
    }

    /**
     * Removes the specified item from the database
     * @param context
     * @param item
     */
    static void deleteItemFromDatabase(Context context, final ItemInfo item) {
        final ContentResolver cr = context.getContentResolver();
        final Uri uriToDelete = LauncherSettings.Favorites.getContentUri(item.id, false);
        Runnable r = new Runnable() {
            public void run() {
                cr.delete(uriToDelete, null, null);
                switch (item.itemType) {
                    case LauncherSettings.Favorites.ITEM_TYPE_FOLDER:
                        sFolders.remove(item.id);
                        sWorkspaceItems.remove(item);
                        break;
                    case LauncherSettings.Favorites.ITEM_TYPE_APPLICATION:
                    case LauncherSettings.Favorites.ITEM_TYPE_SHORTCUT:
                        sWorkspaceItems.remove(item);
                        break;
                    case LauncherSettings.Favorites.ITEM_TYPE_APPWIDGET:
                        sAppWidgets.remove((LauncherAppWidgetInfo) item);
                        break;
                }
                sItemsIdMap.remove(item.id);
                sDbIconCache.remove(item);
            }
        };
        if (sWorkerThread.getThreadId() == Process.myTid()) {
            r.run();
        } else {
            sWorker.post(r);
        }
    }

    /**
     * Remove the contents of the specified folder from the database
     */
    static void deleteFolderContentsFromDatabase(Context context, final FolderInfo info) {
        final ContentResolver cr = context.getContentResolver();

        Runnable r = new Runnable() {
            public void run() {
                cr.delete(LauncherSettings.Favorites.getContentUri(info.id, false), null, null);
                sItemsIdMap.remove(info.id);
                sFolders.remove(info.id);
                sDbIconCache.remove(info);
                sWorkspaceItems.remove(info);

                cr.delete(LauncherSettings.Favorites.CONTENT_URI_NO_NOTIFICATION,
                        LauncherSettings.Favorites.CONTAINER + "=" + info.id, null);
                for (ItemInfo childInfo : info.contents) {
                    sItemsIdMap.remove(childInfo.id);
                    sDbIconCache.remove(childInfo);
                }
            }
        };
        if (sWorkerThread.getThreadId() == Process.myTid()) {
            r.run();
        } else {
            sWorker.post(r);
        }
    }

    /**
     * Set this as the current Launcher activity object for the loader.
     */
    public void initialize(Callbacks callbacks) {
        synchronized (mLock) {
            mCallbacks = new WeakReference<Callbacks>(callbacks);
        }
    }

    /**
     * Call from the handler for ACTION_PACKAGE_ADDED, ACTION_PACKAGE_REMOVED and
     * ACTION_PACKAGE_CHANGED.
     */
    @Override
    public void onReceive(Context context, Intent intent) {
        if (DEBUG_LOADERS) Log.d(TAG, "onReceive intent=" + intent);

        final String action = intent.getAction();

        if (Intent.ACTION_PACKAGE_CHANGED.equals(action)
                || Intent.ACTION_PACKAGE_REMOVED.equals(action)
                || Intent.ACTION_PACKAGE_ADDED.equals(action)) {
            final String packageName = intent.getData().getSchemeSpecificPart();
            final boolean replacing = intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);

            int op = PackageUpdatedTask.OP_NONE;

            if (packageName == null || packageName.length() == 0) {
                // they sent us a bad intent
                return;
            }

            if (Intent.ACTION_PACKAGE_CHANGED.equals(action)) {
                op = PackageUpdatedTask.OP_UPDATE;
            } else if (Intent.ACTION_PACKAGE_REMOVED.equals(action)) {
                if (!replacing) {
                    op = PackageUpdatedTask.OP_REMOVE;
                }
                // else, we are replacing the package, so a PACKAGE_ADDED will be sent
                // later, we will update the package at this time
            } else if (Intent.ACTION_PACKAGE_ADDED.equals(action)) {
                if (!replacing) {
                    op = PackageUpdatedTask.OP_ADD;
                } else {
                    op = PackageUpdatedTask.OP_UPDATE;
                }
            }

            if (op != PackageUpdatedTask.OP_NONE) {
                enqueuePackageUpdated(new PackageUpdatedTask(op, new String[] { packageName }));
            }

        } else if (Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE.equals(action)) {
            // First, schedule to add these apps back in.
            String[] packages = intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
            enqueuePackageUpdated(new PackageUpdatedTask(PackageUpdatedTask.OP_ADD, packages));
            // Then, rebind everything.
            startLoaderFromBackground();
        } else if (Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE.equals(action)) {
            String[] packages = intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
            enqueuePackageUpdated(new PackageUpdatedTask(
                        PackageUpdatedTask.OP_UNAVAILABLE, packages));
        } else if (Intent.ACTION_LOCALE_CHANGED.equals(action)) {
            // If we have changed locale we need to clear out the labels in all apps/workspace.
            forceReload();
        } else if (Intent.ACTION_CONFIGURATION_CHANGED.equals(action)) {
             // Check if configuration change was an mcc/mnc change which would affect app resources
             // and we would need to clear out the labels in all apps/workspace. Same handling as
             // above for ACTION_LOCALE_CHANGED
             Configuration currentConfig = context.getResources().getConfiguration();
             if (mPreviousConfigMcc != currentConfig.mcc) {
                   Log.d(TAG, "Reload apps on config change. curr_mcc:"
                       + currentConfig.mcc + " prevmcc:" + mPreviousConfigMcc);
                   forceReload();
             }
             // Update previousConfig
             mPreviousConfigMcc = currentConfig.mcc;
        } else if (SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED.equals(action) ||
                   SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED.equals(action)) {
            if (mCallbacks != null) {
                Callbacks callbacks = mCallbacks.get();
                if (callbacks != null) {
                    callbacks.bindSearchablesChanged();
                }
            }
        }
    }

    private void forceReload() {
        synchronized (mLock) {
            // Stop any existing loaders first, so they don't set mAllAppsLoaded or
            // mWorkspaceLoaded to true later
            stopLoaderLocked();
            mAllAppsLoaded = false;
            mWorkspaceLoaded = false;
        }
        // Do this here because if the launcher activity is running it will be restarted.
        // If it's not running startLoaderFromBackground will merely tell it that it needs
        // to reload.
        startLoaderFromBackground();
    }

    /**
     * When the launcher is in the background, it's possible for it to miss paired
     * configuration changes.  So whenever we trigger the loader from the background
     * tell the launcher that it needs to re-run the loader when it comes back instead
     * of doing it now.
     */
    public void startLoaderFromBackground() {
        boolean runLoader = false;
        if (mCallbacks != null) {
            Callbacks callbacks = mCallbacks.get();
            if (callbacks != null) {
                // Only actually run the loader if they're not paused.
                if (!callbacks.setLoadOnResume()) {
                    runLoader = true;
                }
            }
        }
        if (runLoader) {
            startLoader(mApp, false);
        }
    }

    // If there is already a loader task running, tell it to stop.
    // returns true if isLaunching() was true on the old task
    private boolean stopLoaderLocked() {
        boolean isLaunching = false;
        LoaderTask oldTask = mLoaderTask;
        if (oldTask != null) {
            if (oldTask.isLaunching()) {
                isLaunching = true;
            }
            oldTask.stopLocked();
        }
        return isLaunching;
    }

    public void startLoader(Context context, boolean isLaunching) {
        synchronized (mLock) {
            if (DEBUG_LOADERS) {
                Log.d(TAG, "startLoader isLaunching=" + isLaunching);
            }

            // Don't bother to start the thread if we know it's not going to do anything
            if (mCallbacks != null && mCallbacks.get() != null) {
                // If there is already one running, tell it to stop.
                // also, don't downgrade isLaunching if we're already running
                isLaunching = isLaunching || stopLoaderLocked();
                mLoaderTask = new LoaderTask(context, isLaunching);
                sWorkerThread.setPriority(Thread.NORM_PRIORITY);
                sWorker.post(mLoaderTask);
            }
        }
    }

    public void stopLoader() {
        synchronized (mLock) {
            if (mLoaderTask != null) {
                mLoaderTask.stopLocked();
            }
        }
    }

    public boolean isAllAppsLoaded() {
        return mAllAppsLoaded;
    }

    /**
     * Runnable for the thread that loads the contents of the launcher:
     *   - workspace icons
     *   - widgets
     *   - all apps icons
     */
    private class LoaderTask implements Runnable {
        private Context mContext;
        private Thread mWaitThread;
        private boolean mIsLaunching;
        private boolean mStopped;
        private boolean mLoadAndBindStepFinished;
        private HashMap<Object, CharSequence> mLabelCache;

        LoaderTask(Context context, boolean isLaunching) {
            mContext = context;
            mIsLaunching = isLaunching;
            mLabelCache = new HashMap<Object, CharSequence>();
        }

        boolean isLaunching() {
            return mIsLaunching;
        }

        private void loadAndBindWorkspace() {
            // Load the workspace
            if (DEBUG_LOADERS) {
                Log.d(TAG, "loadAndBindWorkspace mWorkspaceLoaded=" + mWorkspaceLoaded);
            }

            if (!mWorkspaceLoaded) {
                loadWorkspace();
                synchronized (LoaderTask.this) {
                    if (mStopped) {
                        return;
                    }
                    mWorkspaceLoaded = true;
                }
            }

            // Bind the workspace
            bindWorkspace();
        }

        private void waitForIdle() {
            // Wait until the either we're stopped or the other threads are done.
            // This way we don't start loading all apps until the workspace has settled
            // down.
            synchronized (LoaderTask.this) {
                final long workspaceWaitTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;

                mHandler.postIdle(new Runnable() {
                        public void run() {
                            synchronized (LoaderTask.this) {
                                mLoadAndBindStepFinished = true;
                                if (DEBUG_LOADERS) {
                                    Log.d(TAG, "done with previous binding step");
                                }
                                LoaderTask.this.notify();
                            }
                        }
                    });

                while (!mStopped && !mLoadAndBindStepFinished) {
                    try {
                        this.wait();
                    } catch (InterruptedException ex) {
                        // Ignore
                    }
                }
                if (DEBUG_LOADERS) {
                    Log.d(TAG, "waited "
                            + (SystemClock.uptimeMillis()-workspaceWaitTime)
                            + "ms for previous step to finish binding");
                }
            }
        }

        public void run() {
            // Optimize for end-user experience: if the Launcher is up and // running with the
            // All Apps interface in the foreground, load All Apps first. Otherwise, load the
            // workspace first (default).
            final Callbacks cbk = mCallbacks.get();
            final boolean loadWorkspaceFirst = cbk != null ? (!cbk.isAllAppsVisible()) : true;

            keep_running: {
                // Elevate priority when Home launches for the first time to avoid
                // starving at boot time. Staring at a blank home is not cool.
                synchronized (mLock) {
                    if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to " +
                            (mIsLaunching ? "DEFAULT" : "BACKGROUND"));
                    android.os.Process.setThreadPriority(mIsLaunching
                            ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);
                }
                if (loadWorkspaceFirst) {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");
                    loadAndBindWorkspace();
                } else {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: special: loading all apps");
                    loadAndBindAllApps();
                }

                if (mStopped) {
                    break keep_running;
                }

                // Whew! Hard work done.  Slow us down, and wait until the UI thread has
                // settled down.
                synchronized (mLock) {
                    if (mIsLaunching) {
                        if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to BACKGROUND");
                        android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
                    }
                }
                waitForIdle();

                // second step
                if (loadWorkspaceFirst) {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: loading all apps");
                    loadAndBindAllApps();
                } else {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 2: special: loading workspace");
                    loadAndBindWorkspace();
                }

                // Restore the default thread priority after we are done loading items
                synchronized (mLock) {
                    android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
                }
            }


            // Update the saved icons if necessary
            if (DEBUG_LOADERS) Log.d(TAG, "Comparing loaded icons to database icons");
            for (Object key : sDbIconCache.keySet()) {
                updateSavedIcon(mContext, (ShortcutInfo) key, sDbIconCache.get(key));
            }
            sDbIconCache.clear();

            // Clear out this reference, otherwise we end up holding it until all of the
            // callback runnables are done.
            mContext = null;

            synchronized (mLock) {
                // If we are still the last one to be scheduled, remove ourselves.
                if (mLoaderTask == this) {
                    mLoaderTask = null;
                }
            }
        }

        public void stopLocked() {
            synchronized (LoaderTask.this) {
                mStopped = true;
                this.notify();
            }
        }

        /**
         * Gets the callbacks object.  If we've been stopped, or if the launcher object
         * has somehow been garbage collected, return null instead.  Pass in the Callbacks
         * object that was around when the deferred message was scheduled, and if there's
         * a new Callbacks object around then also return null.  This will save us from
         * calling onto it with data that will be ignored.
         */
        Callbacks tryGetCallbacks(Callbacks oldCallbacks) {
            synchronized (mLock) {
                if (mStopped) {
                    return null;
                }

                if (mCallbacks == null) {
                    return null;
                }

                final Callbacks callbacks = mCallbacks.get();
                if (callbacks != oldCallbacks) {
                    return null;
                }
                if (callbacks == null) {
                    Log.w(TAG, "no mCallbacks");
                    return null;
                }

                return callbacks;
            }
        }

        // check & update map of what's occupied; used to discard overlapping/invalid items
        private boolean checkItemPlacement(ItemInfo occupied[][][], ItemInfo item) {
            int containerIndex = item.screen;
            if (item.container == LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
                // Return early if we detect that an item is under the hotseat button
                if (Hotseat.isAllAppsButtonRank(item.screen)) {
                    return false;
                }

                // We use the last index to refer to the hotseat and the screen as the rank, so
                // test and update the occupied state accordingly
                if (occupied[Launcher.SCREEN_COUNT][item.screen][0] != null) {
                    Log.e(TAG, "Error loading shortcut into hotseat " + item
                        + " into position (" + item.screen + ":" + item.cellX + "," + item.cellY
                        + ") occupied by " + occupied[Launcher.SCREEN_COUNT][item.screen][0]);
                    return false;
                } else {
                    occupied[Launcher.SCREEN_COUNT][item.screen][0] = item;
                    return true;
                }
            } else if (item.container != LauncherSettings.Favorites.CONTAINER_DESKTOP) {
                // Skip further checking if it is not the hotseat or workspace container
                return true;
            }

            // Check if any workspace icons overlap with each other
            for (int x = item.cellX; x < (item.cellX+item.spanX); x++) {
                for (int y = item.cellY; y < (item.cellY+item.spanY); y++) {
                    if (occupied[containerIndex][x][y] != null) {
                        Log.e(TAG, "Error loading shortcut " + item
                            + " into cell (" + containerIndex + "-" + item.screen + ":"
                            + x + "," + y
                            + ") occupied by "
                            + occupied[containerIndex][x][y]);
                        return false;
                    }
                }
            }
            for (int x = item.cellX; x < (item.cellX+item.spanX); x++) {
                for (int y = item.cellY; y < (item.cellY+item.spanY); y++) {
                    occupied[containerIndex][x][y] = item;
                }
            }

            return true;
        }

        private void loadWorkspace() {
            final long t = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;

            final Context context = mContext;
            final ContentResolver contentResolver = context.getContentResolver();
            final PackageManager manager = context.getPackageManager();
            final AppWidgetManager widgets = AppWidgetManager.getInstance(context);
            final boolean isSafeMode = manager.isSafeMode();

            sWorkspaceItems.clear();
            sAppWidgets.clear();
            sFolders.clear();
            sItemsIdMap.clear();
            sDbIconCache.clear();

            final ArrayList<Long> itemsToRemove = new ArrayList<Long>();

            final Cursor c = contentResolver.query(
                    LauncherSettings.Favorites.CONTENT_URI, null, null, null, null);

            // +1 for the hotseat (it can be larger than the workspace)
            // Load workspace in reverse order to ensure that latest items are loaded first (and
            // before any earlier duplicates)
            final ItemInfo occupied[][][] =
                    new ItemInfo[Launcher.SCREEN_COUNT + 1][mCellCountX + 1][mCellCountY + 1];

            try {
                final int idIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites._ID);
                final int intentIndex = c.getColumnIndexOrThrow
                        (LauncherSettings.Favorites.INTENT);
                final int titleIndex = c.getColumnIndexOrThrow
                        (LauncherSettings.Favorites.TITLE);
                final int iconTypeIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.ICON_TYPE);
                final int iconIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.ICON);
                final int iconPackageIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.ICON_PACKAGE);
                final int iconResourceIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.ICON_RESOURCE);
                final int containerIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.CONTAINER);
                final int itemTypeIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.ITEM_TYPE);
                final int appWidgetIdIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.APPWIDGET_ID);
                final int screenIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.SCREEN);
                final int cellXIndex = c.getColumnIndexOrThrow
                        (LauncherSettings.Favorites.CELLX);
                final int cellYIndex = c.getColumnIndexOrThrow
                        (LauncherSettings.Favorites.CELLY);
                final int spanXIndex = c.getColumnIndexOrThrow
                        (LauncherSettings.Favorites.SPANX);
                final int spanYIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.SPANY);
                final int uriIndex = c.getColumnIndexOrThrow(LauncherSettings.Favorites.URI);
                final int displayModeIndex = c.getColumnIndexOrThrow(
                        LauncherSettings.Favorites.DISPLAY_MODE);

                ShortcutInfo info;
                String intentDescription;
                LauncherAppWidgetInfo appWidgetInfo;
                int container;
                long id;
                Intent intent;

                while (!mStopped && c.moveToNext()) {
                    try {
                        int itemType = c.getInt(itemTypeIndex);

                        switch (itemType) {
                        case LauncherSettings.Favorites.ITEM_TYPE_APPLICATION:
                        case LauncherSettings.Favorites.ITEM_TYPE_SHORTCUT:
                            intentDescription = c.getString(intentIndex);
                            try {
                                intent = Intent.parseUri(intentDescription, 0);
                            } catch (URISyntaxException e) {
                                continue;
                            }

                            if (itemType == LauncherSettings.Favorites.ITEM_TYPE_APPLICATION) {
                                info = getShortcutInfo(manager, intent, context, c, iconIndex,
                                        titleIndex, mLabelCache);
                            } else {
                                info = getShortcutInfo(c, context, iconTypeIndex,
                                        iconPackageIndex, iconResourceIndex, iconIndex,
                                        titleIndex);
                            }

                            if (info != null) {
                                info.intent = intent;
                                info.id = c.getLong(idIndex);
                                container = c.getInt(containerIndex);
                                info.container = container;
                                info.screen = c.getInt(screenIndex);
                                info.cellX = c.getInt(cellXIndex);
                                info.cellY = c.getInt(cellYIndex);

                                // check & update map of what's occupied
                                if (!checkItemPlacement(occupied, info)) {
                                    break;
                                }

                                switch (container) {
                                case LauncherSettings.Favorites.CONTAINER_DESKTOP:
                                case LauncherSettings.Favorites.CONTAINER_HOTSEAT:
                                    sWorkspaceItems.add(info);
                                    break;
                                default:
                                    // Item is in a user folder
                                    FolderInfo folderInfo =
                                            findOrMakeFolder(sFolders, container);
                                    folderInfo.add(info);
                                    break;
                                }
                                sItemsIdMap.put(info.id, info);

                                // now that we've loaded everthing re-save it with the
                                // icon in case it disappears somehow.
                                queueIconToBeChecked(sDbIconCache, info, c, iconIndex);
                            } else {
                                // Failed to load the shortcut, probably because the
                                // activity manager couldn't resolve it (maybe the app
                                // was uninstalled), or the db row was somehow screwed up.
                                // Delete it.
                                id = c.getLong(idIndex);
                                Log.e(TAG, "Error loading shortcut " + id + ", removing it");
                                contentResolver.delete(LauncherSettings.Favorites.getContentUri(
                                            id, false), null, null);
                            }
                            break;

                        case LauncherSettings.Favorites.ITEM_TYPE_FOLDER:
                            id = c.getLong(idIndex);
                            FolderInfo folderInfo = findOrMakeFolder(sFolders, id);

                            folderInfo.title = c.getString(titleIndex);
                            folderInfo.id = id;
                            container = c.getInt(containerIndex);
                            folderInfo.container = container;
                            folderInfo.screen = c.getInt(screenIndex);
                            folderInfo.cellX = c.getInt(cellXIndex);
                            folderInfo.cellY = c.getInt(cellYIndex);

                            // check & update map of what's occupied
                            if (!checkItemPlacement(occupied, folderInfo)) {
                                break;
                            }
                            switch (container) {
                                case LauncherSettings.Favorites.CONTAINER_DESKTOP:
                                case LauncherSettings.Favorites.CONTAINER_HOTSEAT:
                                    sWorkspaceItems.add(folderInfo);
                                    break;
                            }

                            sItemsIdMap.put(folderInfo.id, folderInfo);
                            sFolders.put(folderInfo.id, folderInfo);
                            break;

                        case LauncherSettings.Favorites.ITEM_TYPE_APPWIDGET:
                            // Read all Launcher-specific widget details
                            int appWidgetId = c.getInt(appWidgetIdIndex);
                            id = c.getLong(idIndex);

                            final AppWidgetProviderInfo provider =
                                    widgets.getAppWidgetInfo(appWidgetId);

                            if (!isSafeMode && (provider == null || provider.provider == null ||
                                    provider.provider.getPackageName() == null)) {
                                String log = "Deleting widget that isn't installed anymore: id="
                                    + id + " appWidgetId=" + appWidgetId;
                                Log.e(TAG, log); 
                                Launcher.sDumpLogs.add(log);
                                itemsToRemove.add(id);
                            } else {
                                appWidgetInfo = new LauncherAppWidgetInfo(appWidgetId);
                                appWidgetInfo.id = id;
                                appWidgetInfo.screen = c.getInt(screenIndex);
                                appWidgetInfo.cellX = c.getInt(cellXIndex);
                                appWidgetInfo.cellY = c.getInt(cellYIndex);
                                appWidgetInfo.spanX = c.getInt(spanXIndex);
                                appWidgetInfo.spanY = c.getInt(spanYIndex);

                                container = c.getInt(containerIndex);
                                if (container != LauncherSettings.Favorites.CONTAINER_DESKTOP &&
                                    container != LauncherSettings.Favorites.CONTAINER_HOTSEAT) {
                                    Log.e(TAG, "Widget found where container "
                                        + "!= CONTAINER_DESKTOP nor CONTAINER_HOTSEAT - ignoring!");
                                    continue;
                                }
                                appWidgetInfo.container = c.getInt(containerIndex);

                                // check & update map of what's occupied
                                if (!checkItemPlacement(occupied, appWidgetInfo)) {
                                    break;
                                }
                                sItemsIdMap.put(appWidgetInfo.id, appWidgetInfo);
                                sAppWidgets.add(appWidgetInfo);
                            }
                            break;
                        }
                    } catch (Exception e) {
                        Log.w(TAG, "Desktop items loading interrupted:", e);
                    }
                }
            } finally {
                c.close();
            }

            if (itemsToRemove.size() > 0) {
                ContentProviderClient client = contentResolver.acquireContentProviderClient(
                                LauncherSettings.Favorites.CONTENT_URI);
                // Remove dead items
                for (long id : itemsToRemove) {
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "Removed id = " + id);
                    }
                    // Don't notify content observers
                    try {
                        client.delete(LauncherSettings.Favorites.getContentUri(id, false),
                                null, null);
                    } catch (RemoteException e) {
                        Log.w(TAG, "Could not remove id = " + id);
                    }
                }
            }

            if (DEBUG_LOADERS) {
                Log.d(TAG, "loaded workspace in " + (SystemClock.uptimeMillis()-t) + "ms");
                Log.d(TAG, "workspace layout: ");
                for (int y = 0; y < mCellCountY; y++) {
                    String line = "";
                    for (int s = 0; s < Launcher.SCREEN_COUNT; s++) {
                        if (s > 0) {
                            line += " | ";
                        }
                        for (int x = 0; x < mCellCountX; x++) {
                            line += ((occupied[s][x][y] != null) ? "#" : ".");
                        }
                    }
                    Log.d(TAG, "[ " + line + " ]");
                }
            }
        }

        /**
         * Read everything out of our database.
         */
        private void bindWorkspace() {
            final long t = SystemClock.uptimeMillis();

            // Don't use these two variables in any of the callback runnables.
            // Otherwise we hold a reference to them.
            final Callbacks oldCallbacks = mCallbacks.get();
            if (oldCallbacks == null) {
                // This launcher has exited and nobody bothered to tell us.  Just bail.
                Log.w(TAG, "LoaderTask running with no launcher");
                return;
            }

            int N;
            // Tell the workspace that we're about to start firing items at it
            mHandler.post(new Runnable() {
                public void run() {
                    Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                    if (callbacks != null) {
                        callbacks.startBinding();
                    }
                }
            });

            // Unbind previously bound workspace items to prevent a leak of AppWidgetHostViews.
            final ArrayList<ItemInfo> workspaceItems = unbindWorkspaceItemsOnMainThread();

            // Add the items to the workspace.
            N = workspaceItems.size();
            for (int i=0; i<N; i+=ITEMS_CHUNK) {
                final int start = i;
                final int chunkSize = (i+ITEMS_CHUNK <= N) ? ITEMS_CHUNK : (N-i);
                mHandler.post(new Runnable() {
                    public void run() {
                        Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                        if (callbacks != null) {
                            callbacks.bindItems(workspaceItems, start, start+chunkSize);
                        }
                    }
                });
            }
            // Ensure that we don't use the same folders data structure on the main thread
            final HashMap<Long, FolderInfo> folders = new HashMap<Long, FolderInfo>(sFolders);
            mHandler.post(new Runnable() {
                public void run() {
                    Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                    if (callbacks != null) {
                        callbacks.bindFolders(folders);
                    }
                }
            });
            // Wait until the queue goes empty.
            mHandler.post(new Runnable() {
                public void run() {
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "Going to start binding widgets soon.");
                    }
                }
            });
            // Bind the widgets, one at a time.
            // WARNING: this is calling into the workspace from the background thread,
            // but since getCurrentScreen() just returns the int, we should be okay.  This
            // is just a hint for the order, and if it's wrong, we'll be okay.
            // TODO: instead, we should have that push the current screen into here.
            final int currentScreen = oldCallbacks.getCurrentWorkspaceScreen();
            N = sAppWidgets.size();
            // once for the current screen
            for (int i=0; i<N; i++) {
                final LauncherAppWidgetInfo widget = sAppWidgets.get(i);
                if (widget.screen == currentScreen) {
                    mHandler.post(new Runnable() {
                        public void run() {
                            Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                            if (callbacks != null) {
                                callbacks.bindAppWidget(widget);
                            }
                        }
                    });
                }
            }
            // once for the other screens
            for (int i=0; i<N; i++) {
                final LauncherAppWidgetInfo widget = sAppWidgets.get(i);
                if (widget.screen != currentScreen) {
                    mHandler.post(new Runnable() {
                        public void run() {
                            Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                            if (callbacks != null) {
                                callbacks.bindAppWidget(widget);
                            }
                        }
                    });
                }
            }
            // Tell the workspace that we're done.
            mHandler.post(new Runnable() {
                public void run() {
                    Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                    if (callbacks != null) {
                        callbacks.finishBindingItems();
                    }
                }
            });
            // If we're profiling, this is the last thing in the queue.
            mHandler.post(new Runnable() {
                public void run() {
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "bound workspace in "
                            + (SystemClock.uptimeMillis()-t) + "ms");
                    }
                }
            });
        }

        private void loadAndBindAllApps() {
            if (DEBUG_LOADERS) {
                Log.d(TAG, "loadAndBindAllApps mAllAppsLoaded=" + mAllAppsLoaded);
            }
            if (!mAllAppsLoaded) {
                loadAllAppsByBatch();
                synchronized (LoaderTask.this) {
                    if (mStopped) {
                        return;
                    }
                    mAllAppsLoaded = true;
                }
            } else {
                onlyBindAllApps();
            }
        }

        private void onlyBindAllApps() {
            final Callbacks oldCallbacks = mCallbacks.get();
            if (oldCallbacks == null) {
                // This launcher has exited and nobody bothered to tell us.  Just bail.
                Log.w(TAG, "LoaderTask running with no launcher (onlyBindAllApps)");
                return;
            }

            // shallow copy
            final ArrayList<ApplicationInfo> list
                    = (ArrayList<ApplicationInfo>)mAllAppsList.data.clone();
            mHandler.post(new Runnable() {
                public void run() {
                    final long t = SystemClock.uptimeMillis();
                    final Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                    if (callbacks != null) {
                        callbacks.bindAllApplications(list);
                    }
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "bound all " + list.size() + " apps from cache in "
                                + (SystemClock.uptimeMillis()-t) + "ms");
                    }
                }
            });

        }

        private void loadAllAppsByBatch() {
            final long t = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;

            // Don't use these two variables in any of the callback runnables.
            // Otherwise we hold a reference to them.
            final Callbacks oldCallbacks = mCallbacks.get();
            if (oldCallbacks == null) {
                // This launcher has exited and nobody bothered to tell us.  Just bail.
                Log.w(TAG, "LoaderTask running with no launcher (loadAllAppsByBatch)");
                return;
            }

            final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
            mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

            final PackageManager packageManager = mContext.getPackageManager();
            List<ResolveInfo> apps = null;

            int N = Integer.MAX_VALUE;

            int startIndex;
            int i=0;
            int batchSize = -1;
            while (i < N && !mStopped) {
                if (i == 0) {
                    mAllAppsList.clear();
                    final long qiaTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
                    apps = packageManager.queryIntentActivities(mainIntent, 0);
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "queryIntentActivities took "
                                + (SystemClock.uptimeMillis()-qiaTime) + "ms");
                    }
                    if (apps == null) {
                        return;
                    }
                    N = apps.size();
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "queryIntentActivities got " + N + " apps");
                    }
                    if (N == 0) {
                        // There are no apps?!?
                        return;
                    }
                    if (mBatchSize == 0) {
                        batchSize = N;
                    } else {
                        batchSize = mBatchSize;
                    }

                    final long sortTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
                    Collections.sort(apps,
                            new LauncherModel.ShortcutNameComparator(packageManager, mLabelCache));
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "sort took "
                                + (SystemClock.uptimeMillis()-sortTime) + "ms");
                    }
                }

                final long t2 = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;

                startIndex = i;
                for (int j=0; i<N && j<batchSize; j++) {
                    // This builds the icon bitmaps.
                    mAllAppsList.add(new ApplicationInfo(packageManager, apps.get(i),
                            mIconCache, mLabelCache));
                    i++;
                }

                final boolean first = i <= batchSize;
                final Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                final ArrayList<ApplicationInfo> added = mAllAppsList.added;
                mAllAppsList.added = new ArrayList<ApplicationInfo>();

                mHandler.post(new Runnable() {
                    public void run() {
                        final long t = SystemClock.uptimeMillis();
                        if (callbacks != null) {
                            if (first) {
                                callbacks.bindAllApplications(added);
                            } else {
                                callbacks.bindAppsAdded(added);
                            }
                            if (DEBUG_LOADERS) {
                                Log.d(TAG, "bound " + added.size() + " apps in "
                                    + (SystemClock.uptimeMillis() - t) + "ms");
                            }
                        } else {
                            Log.i(TAG, "not binding apps: no Launcher activity");
                        }
                    }
                });

                if (DEBUG_LOADERS) {
                    Log.d(TAG, "batch of " + (i-startIndex) + " icons processed in "
                            + (SystemClock.uptimeMillis()-t2) + "ms");
                }

                if (mAllAppsLoadDelay > 0 && i < N) {
                    try {
                        if (DEBUG_LOADERS) {
                            Log.d(TAG, "sleeping for " + mAllAppsLoadDelay + "ms");
                        }
                        Thread.sleep(mAllAppsLoadDelay);
                    } catch (InterruptedException exc) { }
                }
            }

            if (DEBUG_LOADERS) {
                Log.d(TAG, "cached all " + N + " apps in "
                        + (SystemClock.uptimeMillis()-t) + "ms"
                        + (mAllAppsLoadDelay > 0 ? " (including delay)" : ""));
            }
        }

        public void dumpState() {
            Log.d(TAG, "mLoaderTask.mContext=" + mContext);
            Log.d(TAG, "mLoaderTask.mWaitThread=" + mWaitThread);
            Log.d(TAG, "mLoaderTask.mIsLaunching=" + mIsLaunching);
            Log.d(TAG, "mLoaderTask.mStopped=" + mStopped);
            Log.d(TAG, "mLoaderTask.mLoadAndBindStepFinished=" + mLoadAndBindStepFinished);
            Log.d(TAG, "mItems size=" + sWorkspaceItems.size());
        }
    }

    void enqueuePackageUpdated(PackageUpdatedTask task) {
        sWorker.post(task);
    }

    private class PackageUpdatedTask implements Runnable {
        int mOp;
        String[] mPackages;

        public static final int OP_NONE = 0;
        public static final int OP_ADD = 1;
        public static final int OP_UPDATE = 2;
        public static final int OP_REMOVE = 3; // uninstlled
        public static final int OP_UNAVAILABLE = 4; // external media unmounted


        public PackageUpdatedTask(int op, String[] packages) {
            mOp = op;
            mPackages = packages;
        }

        public void run() {
            final Context context = mApp;

            final String[] packages = mPackages;
            final int N = packages.length;
            switch (mOp) {
                case OP_ADD:
                    for (int i=0; i<N; i++) {
                        if (DEBUG_LOADERS) Log.d(TAG, "mAllAppsList.addPackage " + packages[i]);
                        mAllAppsList.addPackage(context, packages[i]);
                    }
                    break;
                case OP_UPDATE:
                    for (int i=0; i<N; i++) {
                        if (DEBUG_LOADERS) Log.d(TAG, "mAllAppsList.updatePackage " + packages[i]);
                        mAllAppsList.updatePackage(context, packages[i]);
                    }
                    break;
                case OP_REMOVE:
                case OP_UNAVAILABLE:
                    for (int i=0; i<N; i++) {
                        if (DEBUG_LOADERS) Log.d(TAG, "mAllAppsList.removePackage " + packages[i]);
                        mAllAppsList.removePackage(packages[i]);
                    }
                    break;
            }

            ArrayList<ApplicationInfo> added = null;
            ArrayList<ApplicationInfo> removed = null;
            ArrayList<ApplicationInfo> modified = null;

            if (mAllAppsList.added.size() > 0) {
                added = mAllAppsList.added;
                mAllAppsList.added = new ArrayList<ApplicationInfo>();
            }
            if (mAllAppsList.removed.size() > 0) {
                removed = mAllAppsList.removed;
                mAllAppsList.removed = new ArrayList<ApplicationInfo>();
                for (ApplicationInfo info: removed) {
                    mIconCache.remove(info.intent.getComponent());
                }
            }
            if (mAllAppsList.modified.size() > 0) {
                modified = mAllAppsList.modified;
                mAllAppsList.modified = new ArrayList<ApplicationInfo>();
            }

            final Callbacks callbacks = mCallbacks != null ? mCallbacks.get() : null;
            if (callbacks == null) {
                Log.w(TAG, "Nobody to tell about the new app.  Launcher is probably loading.");
                return;
            }

            if (added != null) {
                final ArrayList<ApplicationInfo> addedFinal = added;
                mHandler.post(new Runnable() {
                    public void run() {
                        Callbacks cb = mCallbacks != null ? mCallbacks.get() : null;
                        if (callbacks == cb && cb != null) {
                            callbacks.bindAppsAdded(addedFinal);
                        }
                    }
                });
            }
            if (modified != null) {
                final ArrayList<ApplicationInfo> modifiedFinal = modified;
                mHandler.post(new Runnable() {
                    public void run() {
                        Callbacks cb = mCallbacks != null ? mCallbacks.get() : null;
                        if (callbacks == cb && cb != null) {
                            callbacks.bindAppsUpdated(modifiedFinal);
                        }
                    }
                });
            }
            if (removed != null) {
                final boolean permanent = mOp != OP_UNAVAILABLE;
                final ArrayList<ApplicationInfo> removedFinal = removed;
                mHandler.post(new Runnable() {
                    public void run() {
                        Callbacks cb = mCallbacks != null ? mCallbacks.get() : null;
                        if (callbacks == cb && cb != null) {
                            callbacks.bindAppsRemoved(removedFinal, permanent);
                        }
                    }
                });
            }

            mHandler.post(new Runnable() {
                @Override
                public void run() {
                    Callbacks cb = mCallbacks != null ? mCallbacks.get() : null;
                    if (callbacks == cb && cb != null) {
                        callbacks.bindPackagesUpdated();
                    }
                }
            });
        }
    }

    /**
     * This is called from the code that adds shortcuts from the intent receiver.  This
     * doesn't have a Cursor, but
     */
    public ShortcutInfo getShortcutInfo(PackageManager manager, Intent intent, Context context) {
        return getShortcutInfo(manager, intent, context, null, -1, -1, null);
    }

    /**
     * Make an ShortcutInfo object for a shortcut that is an application.
     *
     * If c is not null, then it will be used to fill in missing data like the title and icon.
     */
    public ShortcutInfo getShortcutInfo(PackageManager manager, Intent intent, Context context,
            Cursor c, int iconIndex, int titleIndex, HashMap<Object, CharSequence> labelCache) {
        Bitmap icon = null;
        final ShortcutInfo info = new ShortcutInfo();

        ComponentName componentName = intent.getComponent();
        if (componentName == null) {
            return null;
        }

        // TODO: See if the PackageManager knows about this case.  If it doesn't
        // then return null & delete this.

        // the resource -- This may implicitly give us back the fallback icon,
        // but don't worry about that.  All we're doing with usingFallbackIcon is
        // to avoid saving lots of copies of that in the database, and most apps
        // have icons anyway.
        final ResolveInfo resolveInfo = manager.resolveActivity(intent, 0);
        if (resolveInfo != null) {
            icon = mIconCache.getIcon(componentName, resolveInfo, labelCache);
        }
        // the db
        if (icon == null) {
            if (c != null) {
                icon = getIconFromCursor(c, iconIndex, context);
            }
        }
        // the fallback icon
        if (icon == null) {
            icon = getFallbackIcon();
            info.usingFallbackIcon = true;
        }
        info.setIcon(icon);

        // from the resource
        if (resolveInfo != null) {
            ComponentName key = LauncherModel.getComponentNameFromResolveInfo(resolveInfo);
            if (labelCache != null && labelCache.containsKey(key)) {
                info.title = labelCache.get(key);
            } else {
                info.title = resolveInfo.activityInfo.loadLabel(manager);
                if (labelCache != null) {
                    labelCache.put(key, info.title);
                }
            }
        }
        // from the db
        if (info.title == null) {
            if (c != null) {
                info.title =  c.getString(titleIndex);
            }
        }
        // fall back to the class name of the activity
        if (info.title == null) {
            info.title = componentName.getClassName();
        }
        info.itemType = LauncherSettings.Favorites.ITEM_TYPE_APPLICATION;
        return info;
    }

    /**
     * Make an ShortcutInfo object for a shortcut that isn't an application.
     */
    private ShortcutInfo getShortcutInfo(Cursor c, Context context,
            int iconTypeIndex, int iconPackageIndex, int iconResourceIndex, int iconIndex,
            int titleIndex) {

        Bitmap icon = null;
        final ShortcutInfo info = new ShortcutInfo();
        info.itemType = LauncherSettings.Favorites.ITEM_TYPE_SHORTCUT;

        // TODO: If there's an explicit component and we can't install that, delete it.

        info.title = c.getString(titleIndex);

        int iconType = c.getInt(iconTypeIndex);
        switch (iconType) {
        case LauncherSettings.Favorites.ICON_TYPE_RESOURCE:
            String packageName = c.getString(iconPackageIndex);
            String resourceName = c.getString(iconResourceIndex);
            PackageManager packageManager = context.getPackageManager();
            info.customIcon = false;
            // the resource
            try {
                Resources resources = packageManager.getResourcesForApplication(packageName);
                if (resources != null) {
                    final int id = resources.getIdentifier(resourceName, null, null);
                    icon = Utilities.createIconBitmap(
                            mIconCache.getFullResIcon(resources, id), context);
                }
            } catch (Exception e) {
                // drop this.  we have other places to look for icons
            }
            // the db
            if (icon == null) {
                icon = getIconFromCursor(c, iconIndex, context);
            }
            // the fallback icon
            if (icon == null) {
                icon = getFallbackIcon();
                info.usingFallbackIcon = true;
            }
            break;
        case LauncherSettings.Favorites.ICON_TYPE_BITMAP:
            icon = getIconFromCursor(c, iconIndex, context);
            if (icon == null) {
                icon = getFallbackIcon();
                info.customIcon = false;
                info.usingFallbackIcon = true;
            } else {
                info.customIcon = true;
            }
            break;
        default:
            icon = getFallbackIcon();
            info.usingFallbackIcon = true;
            info.customIcon = false;
            break;
        }
        info.setIcon(icon);
        return info;
    }

    Bitmap getIconFromCursor(Cursor c, int iconIndex, Context context) {
        if (false) {
            Log.d(TAG, "getIconFromCursor app="
                    + c.getString(c.getColumnIndexOrThrow(LauncherSettings.Favorites.TITLE)));
        }
        byte[] data = http://www.mamicode.com/c.getBlob(iconIndex);>


下面的DeferredHandler有心者可以学习学习::


/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.launcher2;

import java.util.LinkedList;

import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.os.MessageQueue;

/**
 * Queue of things to run on a looper thread.  Items posted with {@link #post} will not
 * be actually enqued on the handler until after the last one has run, to keep from
 * starving the thread.
 *
 * This class is fifo.
 */
public class DeferredHandler {
    private LinkedList<Runnable> mQueue = new LinkedList<Runnable>();
    private MessageQueue mMessageQueue = Looper.myQueue();
    private Impl mHandler = new Impl();

    private class Impl extends Handler implements MessageQueue.IdleHandler {
        public void handleMessage(Message msg) {
            Runnable r;
            synchronized (mQueue) {
                if (mQueue.size() == 0) {
                    return;
                }
                r = mQueue.removeFirst();
            }
            r.run();
            synchronized (mQueue) {
                scheduleNextLocked();
            }
        }

        public boolean queueIdle() {
            handleMessage(null);
            return false;
        }
    }

    private class IdleRunnable implements Runnable {
        Runnable mRunnable;

        IdleRunnable(Runnable r) {
            mRunnable = r;
        }

        public void run() {
            mRunnable.run();
        }
    }

    public DeferredHandler() {
    }

    /** Schedule runnable to run after everything that's on the queue right now. */
    public void post(Runnable runnable) {
        synchronized (mQueue) {
            mQueue.add(runnable);
            if (mQueue.size() == 1) {
                scheduleNextLocked();
            }
        }
    }

    /** Schedule runnable to run when the queue goes idle. */
    public void postIdle(final Runnable runnable) {
        post(new IdleRunnable(runnable));
    }

    public void cancelRunnable(Runnable runnable) {
        synchronized (mQueue) {
            while (mQueue.remove(runnable)) { }
        }
    }

    public void cancel() {
        synchronized (mQueue) {
            mQueue.clear();
        }
    }

    void scheduleNextLocked() {
        if (mQueue.size() > 0) {
        	// 憋、偷窥
            Runnable peek = mQueue.getFirst();
            if (peek instanceof IdleRunnable) {
                mMessageQueue.addIdleHandler(mHandler);
            } else {
                mHandler.sendEmptyMessage(1);
            }
        }
    }
}

这里呢,运用了两个Handler跟两个Loop,DeferredHandler使用的是主线程中的Loop,sWorker使用的是HandlerThread中的Loop,这里为何使用两个Handler跟两个Loop,因为这里一个sWorker.post里面又调用了mHandler.post,如果只用一个Loop会出现死循环的情况!


既然都说到这里,再给大家来个大礼包:TurAsyncTask.java

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.turbo.common;


import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;

import android.os.AsyncTask;

/**
 * {@link AsyncTask} substitution for the email app.
 *
 * Modeled after {@link AsyncTask}; the basic usage is the same, with extra features:
 * - Bulk cancellation of multiple tasks.  This is mainly used by UI to cancel pending tasks
 *   in onDestroy() or similar places.
 * - Instead of {@link AsyncTask#onPostExecute}, it has {@link #onSuccess(Object)}, as the
 *   regular {@link AsyncTask#onPostExecute} is a bit hard to predict when it'll be called and
 *   whel it won't.
 *
 * Note this class is missing some of the {@link AsyncTask} features, e.g. it lacks
 * {@link AsyncTask#onProgressUpdate}.  Add these when necessary.
 */

/**
 * AsyncTask管理类,可以同时退出,并且可以设置执行是否同时还是顺序执行
 * @author Turbo
 *
 */
public abstract class TurAsyncTask<Params, Progress, Result> {
	// 连续执行
    private static final Executor SERIAL_EXECUTOR = AsyncTask.SERIAL_EXECUTOR;
    // 线程池执行,并发执行
    private static final Executor PARALLEL_EXECUTOR = AsyncTask.THREAD_POOL_EXECUTOR;
    /// M: define a few independent customized serial executors for auto clean attachment task. @{
    // 自定义的执行方式,优先执行当前的异步任务,其他的执行结束之后并发执行
    public static final Executor SERIAL_EXECUTOR_FOR_AUTO_CLEAR_ATTACH = new TurboSerialExecutor();
    /// @}
    
    //3.0后新增了一个方法executeOnExecutor(Executor exec, Object... params),
    //该方法接受2个参数,第一个是Executor,第二个是任务参数。第一个是线程池实例,google为我们预定义了两种:
    //第一种是AsyncTask.SERIAL_EXECUTOR,第二种是AsyncTask.THREAD_POOL_EXECUTOR,顾名思义,第一
    //种其实就像3.0以后的execute方法,是顺序执行的。第二种就是3.0以前的execute方法,是可以并发执行的。我们直
    //接用asyncTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, task);就可以多任务并发执行了。
    /**j
     * M: adding for using independent customized executors for specified email task.
     */
    private static class TurboSerialExecutor implements Executor {
    	// 集合
        final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>();
        Runnable mActive;

        // Android中的HashMap被 SparseIntArray代替
        public synchronized void execute(final Runnable r) {
            mTasks.offer(new Runnable() {
                public void run() {
                    try {
                        r.run();
                    } finally {
                        scheduleNext();
                    }
                }
            });
            if (mActive == null) {
                scheduleNext();
            }
        }

        /**
         * 
         */
        protected synchronized void scheduleNext() {
            if ((mActive = mTasks.poll()) != null) {
            	// 执行器可用于并行执行任务。
                AsyncTask.THREAD_POOL_EXECUTOR.execute(mActive);
            }
        }
    }

    /**
     * Tracks {@link TurAsyncTask}.
     *
     * Call {@link #cancellAllInterrupt()} to cancel all tasks registered.
     */
    public  static class Tracker {
        private final LinkedList<TurAsyncTask<?, ?, ?>> mTasks =
                new LinkedList<TurAsyncTask<?, ?, ?>>();

        private void add(TurAsyncTask<?, ?, ?> task) {
            synchronized (mTasks) {
                mTasks.add(task);
            }
        }

        private void remove(TurAsyncTask<?, ?, ?> task) {
            synchronized (mTasks) {
                mTasks.remove(task);
            }
        }

        /**
         * Cancel all registered tasks.
         */
        public void cancellAllInterrupt() {
            synchronized (mTasks) {
                for (TurAsyncTask<?, ?, ?> task : mTasks) {
                    task.cancel(true);
                }
                mTasks.clear();
            }
        }

        /**
         * Cancel all instances of the same class as {@code current} other than
         * {@code current} itself.
         */
        /* package */ void cancelOthers(TurAsyncTask<?, ?, ?> current) {
            final Class<?> clazz = current.getClass();
            synchronized (mTasks) {
                final ArrayList<TurAsyncTask<?, ?, ?>> toRemove =
                        new ArrayList<TurAsyncTask<?, ?, ?>>();
                for (TurAsyncTask<?, ?, ?> task : mTasks) {
                    if ((task != current) && task.getClass().equals(clazz)) {
                        task.cancel(true);
                        toRemove.add(task);
                    }
                }
                for (TurAsyncTask<?, ?, ?> task : toRemove) {
                    mTasks.remove(task);
                }
            }
        }

        /* package */ int getTaskCountForTest() {
            return mTasks.size();
        }

        /* package */ boolean containsTaskForTest(TurAsyncTask<?, ?, ?> task) {
            return mTasks.contains(task);
        }
    }

    private final Tracker mTracker;

    /**
     * AsyncTask
     * @author Turbo
     *
     * @param <Params2>
     * @param <Progress2>
     * @param <Result2>
     */
    private static class InnerTask<Params2, Progress2, Result2>
            extends AsyncTask<Params2, Progress2, Result2> {
        private final TurAsyncTask<Params2, Progress2, Result2> mOwner;

        public InnerTask(TurAsyncTask<Params2, Progress2, Result2> owner) {
            mOwner = owner;
        }

        @Override
        protected Result2 doInBackground(Params2... params) {
            return mOwner.doInBackground(params);
        }

        @Override
        public void onCancelled(Result2 result) {
            mOwner.unregisterSelf();
            mOwner.onCancelled(result);
        }

        @Override
        public void onPostExecute(Result2 result) {
            mOwner.unregisterSelf();
            if (mOwner.mCancelled) {
                mOwner.onCancelled(result);
            } else {
                mOwner.onSuccess(result);
            }
        }
    }

    private final InnerTask<Params, Progress, Result> mInnerTask;
    private volatile boolean mCancelled;

    public TurAsyncTask(Tracker tracker) {
    	// Tracker就是一个AsyncTask管理集合
    	// 初始化此AsyncTask的时候就内部就会将此任务交付给Tracker管理
        mTracker = tracker;
        if (mTracker != null) {
            mTracker.add(this);
        }
        mInnerTask = new InnerTask<Params, Progress, Result>(this);
    }

    // 与集合有关的注册销毁方法
    /* package */ final void unregisterSelf() {
        if (mTracker != null) {
            mTracker.remove(this);
        }
    }

    /** @see AsyncTask#doInBackground */
    protected abstract Result doInBackground(Params... params);


    /** @see AsyncTask#cancel(boolean) */
    public final void cancel(boolean mayInterruptIfRunning) {
        mCancelled = true;
        mInnerTask.cancel(mayInterruptIfRunning);
    }

    /** @see AsyncTask#onCancelled */
    protected void onCancelled(Result result) {
    }

    /**
     * Similar to {@link AsyncTask#onPostExecute}, but this will never be executed if
     * {@link #cancel(boolean)} has been called before its execution, even if
     * {@link #doInBackground(Object...)} has completed when cancelled.
     *
     * @see AsyncTask#onPostExecute
     */
    protected void onSuccess(Result result) {
    }

    /**
     * M : execute on a customized executor.
     *
     * @see AsyncTask#execute
     */
    public final TurAsyncTask<Params, Progress, Result> executeExecutor(Executor executor, Params... params) {
        return executeInternal(executor, false, params);
    }

    /**
     * execute on {@link #PARALLEL_EXECUTOR}
     *
     * @see AsyncTask#execute
     */
    // 异步任务的执行入口
    public final TurAsyncTask<Params, Progress, Result> executeParallel(Params... params) {
        return executeInternal(PARALLEL_EXECUTOR, false, params);
    }

    /**
     * execute on {@link #SERIAL_EXECUTOR}
     *
     * @see AsyncTask#execute
     */
    // 异步任务的执行入口
    public final TurAsyncTask<Params, Progress, Result> executeSerial(Params... params) {
        return executeInternal(SERIAL_EXECUTOR, false, params);
    }

    /**
     * Cancel all previously created instances of the same class tracked by the same
     * {@link Tracker}, and then {@link #executeParallel}.
     */
    public final TurAsyncTask<Params, Progress, Result> cancelPreviousAndExecuteParallel(
            Params... params) {
        return executeInternal(PARALLEL_EXECUTOR, true, params);
    }

    /**
     * Cancel all previously created instances of the same class tracked by the same
     * {@link Tracker}, and then {@link #executeSerial}.
     */
    public final TurAsyncTask<Params, Progress, Result> cancelPreviousAndExecuteSerial(
            Params... params) {
        return executeInternal(SERIAL_EXECUTOR, true, params);
    }

    private final TurAsyncTask<Params, Progress, Result> executeInternal(Executor executor,
            boolean cancelPrevious, Params... params) {
        if (cancelPrevious) {
            if (mTracker == null) {
                throw new IllegalStateException();
            } else {
                mTracker.cancelOthers(this);
            }
        }
        mInnerTask.executeOnExecutor(executor, params);
        return this;
    }

    /**
     * Runs a {@link Runnable} in a bg thread, using {@link #PARALLEL_EXECUTOR}.
     */
    // 开启一个线程
    public static TurAsyncTask<Void, Void, Void> runAsyncParallel(Runnable runnable) {
        return runAsyncInternal(PARALLEL_EXECUTOR, runnable);
    }

    /**
     * Runs a {@link Runnable} in a bg thread, using {@link #SERIAL_EXECUTOR}.
     */
    // 开启一个线程
    public static TurAsyncTask<Void, Void, Void> runAsyncSerial(Runnable runnable) {
        return runAsyncInternal(SERIAL_EXECUTOR, runnable);
    }

    /**
     * 
     * @param executor
     * @param runnable
     * @return
     */
    private static TurAsyncTask<Void, Void, Void> runAsyncInternal(Executor executor,
            final Runnable runnable) {
    	// Runnable并没有加入Tracker中
        TurAsyncTask<Void, Void, Void> task = new TurAsyncTask<Void, Void, Void>(null) {
            @Override
            protected Void doInBackground(Void... params) {
                runnable.run();
                return null;
            }
        };
        return task.executeInternal(executor, false, (Void[]) null);
    }

    /**
     * Wait until {@link #doInBackground} finishes and returns the results of the computation.
     *
     * @see AsyncTask#get
     */
    public final Result get() throws InterruptedException, ExecutionException {
        return mInnerTask.get();
    }

    
    /* package */ final Result callDoInBackgroundForTest(Params... params) {
        return mInnerTask.doInBackground(params);
    }

    /* package */ final void callOnCancelledForTest(Result result) {
        mInnerTask.onCancelled(result);
    }

    /* package */ final void callOnPostExecuteForTest(Result result) {
        mInnerTask.onPostExecute(result);
    }
}

大家可以对比runAsyncParallel/runAsyncSerial跟HandlerThread,除了一个是在主线程,一个是在子线程,其他的底层原理还有啥区别,有啥观点、结论欢迎留言讨论

HandlerThread应用(对比AsyncTask)