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Android_数据库_异步操作封装
/** * A particular {@link AsyncQueryHandler} allowing clients to be notified via a * listener. The {@link NotifyingAsyncQueryHandler} also make sure no strong * reference is kept on the given listener (as it is often a Context). * */ public class DBAsyncHandler extends AsyncQueryHandler { private WeakReference<DBAsyncListener> mListener; /** * Client may use this to listen to completed query operations. run on UI * Thread */ public static class DBAsyncListener { public DBAsyncListener() { } /** * run on UI Thread <br /> * <b>cursor close() method needn't be called</b> */ protected void onQueryComplete(int token, Object cookie, Cursor cursor) { } protected void onInsertComplete(int token, Object cookie, Uri uri) { } protected void onUpdateComplete(int token, Object cookie, int result) { } protected void onDeleteComplete(int token, Object cookie, int result) { } } /**instance in UI Thread*/ public DBAsyncHandler(ContentResolver resolver, DBAsyncListener listener) { super(resolver); setDBListener(listener); } /** * Assign the given {@link DBAsyncListener}. */ public void setDBListener(DBAsyncListener listener) { mListener = (listener != null) ? new WeakReference<DBAsyncListener>(listener) : null; } private DBAsyncListener getDBListener() { return (mListener == null) ? null : mListener.get(); } /** such as Activity-onDestory(), this method is called */ public void clearDBListener() { mListener = null; } public void startQuery(int token, Object cookie, Uri uri, String[] projection, String selection, String[] selectionArgs, String orderBy) { super.startQuery(token, cookie, uri, projection, selection, selectionArgs, orderBy); } @Override protected void onQueryComplete(int token, Object cookie, Cursor cursor) { DBAsyncListener listener = getDBListener(); if (listener != null) { listener.onQueryComplete(token, cookie, cursor); if (cursor != null && !cursor.isClosed()) cursor.close(); } else if (cursor != null) { cursor.close(); } } @Override protected void onDeleteComplete(int token, Object cookie, int result) { DBAsyncListener listener = getDBListener(); if (listener != null) { listener.onDeleteComplete(token, cookie, result); } } @Override protected void onInsertComplete(int token, Object cookie, Uri uri) { DBAsyncListener listener = getDBListener(); if (listener != null) { listener.onInsertComplete(token, cookie, uri); } } @Override protected void onUpdateComplete(int token, Object cookie, int result) { DBAsyncListener listener = getDBListener(); if (listener != null) { listener.onUpdateComplete(token, cookie, result); } } }
public class MyProvider extends ContentProvider { private final static String TAG = MyProvider.class.getSimpleName(); private final static int Person = 1; public final static String BASE = "com.baidu.my.provider"; public final static Uri URI_Person = Uri.parse("content://com.baidu.my.provider/Person"); private final static UriMatcher MATCHER = new UriMatcher(UriMatcher.NO_MATCH); // 如果都匹配不成功,则返回构造函数中指定的参数值,默认为-1 private SQLiteDatabase db; static { MATCHER.addURI(BASE, "Person", Person); } @Override public boolean onCreate() { MyDBHelper dbHelper = new MyDBHelper(this.getContext()); db = dbHelper.getWritableDatabase(); return true; } @Override public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { Cursor c = null; switch (MATCHER.match(uri)) { case Person: c = db.query(DBPerson.TableName, projection, selection, selectionArgs, null, null, sortOrder); c.setNotificationUri(getContext().getContentResolver(), URI_Person); break; default: break; } return c; } @Override public String getType(Uri uri) { switch (MATCHER.match(uri)) { case Person: return "vnd.android.cursor.dir/vnd." + BASE + ".request"; default: break; } return null; } @Override public Uri insert(Uri uri, ContentValues values) { long id = 0; switch (MATCHER.match(uri)) { case Person: id = db.insert(DBPerson.TableName, null, values); if (id > 0) { // 数据发生改变,发出通知 getContext().getContentResolver().notifyChange(URI_Person, null); } return ContentUris.withAppendedId(uri, id); } return null; } @Override public int delete(Uri uri, String selection, String[] selectionArgs) { // TODO Auto-generated method stub return 0; } @Override public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { // TODO Auto-generated method stub return 0; } }
public class MyDBHelper extends SQLiteOpenHelper { private static final String TAG = "DBHelper"; private static final String DB_NAME = "my.db"; private static final int DB_VERSION = /**/ 57 /**/;/****谨慎修改,否则将导致用户历史数据被删除****/ public MyDBHelper(Context context) { super(context, DB_NAME, null, DB_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(getRequestCreateStr()); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + DBPerson.TableName); onCreate(db); } private String getRequestCreateStr() { StringBuffer sb = new StringBuffer(); sb.append("CREATE TABLE ").append(DBPerson.TableName); sb.append(" ("); sb.append(BaseColumns._ID).append(" INTEGER PRIMARY KEY,"); sb.append(DBPerson.MetaDate.Name).append(" TEXT,"); sb.append(DBPerson.MetaDate.Age).append(" TEXT)"); return sb.toString(); } }
public interface DBPerson extends BaseDB{ public interface MetaDate { String Name = "Name"; String Age = "Age"; } public String TableName = "Person"; public String[] PROJECTION = { MetaDate.Name, MetaDate.Age }; public String SORT_ORDER = MetaDate.Age + " ASC"; }
public class MainActivity extends Activity { private DBAsyncHandler dbAsyncHandler; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // dbAsyncHandler = new DBAsyncHandler(getContentResolver(), dbListener); } private DBAsyncHandler.DBAsyncListener dbListener = new DBAsyncListener() { protected void onQueryComplete(int token, Object cookie, Cursor cursor) { Toast.makeText(getApplicationContext(), "ok = " + cursor.getCount(), 1).show(); } protected void onInsertComplete(int token, Object cookie, android.net.Uri uri) { Toast.makeText(getApplicationContext(), "插入ok!", 1).show(); } }; public void query(View view) { //query dbAsyncHandler.startQuery(100, null, MyProvider.URI_Person, DBPerson.PROJECTION, null, null, DBPerson.SORT_ORDER); } public void insert(View view) { //insert ContentValues initialValues = new ContentValues(); initialValues.put(DBPerson.MetaDate.Name, "baidu"); initialValues.put(DBPerson.MetaDate.Age, System.currentTimeMillis()); dbAsyncHandler.startInsert(100, null, MyProvider.URI_Person, initialValues); } @Override protected void onDestroy() { //clear dbAsyncHandler.clearDBListener(); super.onDestroy(); } }
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Android_数据库_异步操作封装
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