package com.loaderman.appcachedemo;

import android.content.pm.IPackageDataObserver;
import android.content.pm.IPackageStatsObserver;
import android.content.pm.PackageManager;
import android.content.pm.PackageStats;
import android.os.Bundle;
import android.os.RemoteException;
import android.support.v7.app.AppCompatActivity;
import android.text.format.Formatter;
import android.view.View;
import android.widget.Button;

import java.io.File;
import java.io.FileOutputStream;
import java.lang.reflect.Method;

public class MainActivity extends AppCompatActivity {

    private PackageManager mPM;
    private Button btnCache;
    private Button btnClean;

    private long cacheSize;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //模拟缓存
        moniCache();
        btnCache = (Button) findViewById(R.id.btn_cache);
        btnClean = (Button) findViewById(R.id.btn_clean);
        mPM = getPackageManager();
    }

    private void moniCache() {
        //获取当前缓存路径: data/data/包名/cache
        File cacheDir = getCacheDir();
        //往缓存里面写点东西模拟
        File cacheFile = new File(cacheDir, "cache.txt");
        try {
            FileOutputStream out = new FileOutputStream(cacheFile);
            out.write("jfaklsdjfaklsdjfklasdjfkladsfjlkasdjflkasdflkasdjf".getBytes());
            out.flush();
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void startScan(View view) {
        SaoMiaoCache();
    }
    private void SaoMiaoCache() {
        try {
            Method method = mPM.getClass().getMethod("getPackageSizeInfo",
                    String.class, IPackageStatsObserver.class);
                method.invoke(mPM, getPackageName(), new MyObserver());
            } catch (Exception e) {
                e.printStackTrace();
            }
    }
    public void cleanCache(View view){
        try {
            Method method = mPM.getClass().getMethod
                    ("freeStorageAndNotify", long.class, IPackageDataObserver.class);
            method.invoke(mPM, Long.MAX_VALUE, new IPackageDataObserver.Stub() {
                //子线程
                @Override
                public void onRemoveCompleted(String packageName, boolean succeeded)
                        throws RemoteException {
                   runOnUiThread(new Runnable() {
                       @Override
                       public void run() {
                           SaoMiaoCache();
                       }
                   });
                }

            });

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    class MyObserver extends IPackageStatsObserver.Stub {

        //在子线程运行
        @Override
        public void onGetStatsCompleted(PackageStats pStats, boolean succeeded) throws
                RemoteException {
            //缓存大小
            cacheSize = pStats.cacheSize;
            System.out.println(cacheSize);
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    btnCache.setText("缓存大小:" + Formatter.formatFileSize(getApplicationContext(), cacheSize));
                }
            });
        }
    }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.loaderman.appcachedemo.MainActivity">

    <Button
        android:id="@+id/btn_cache"
        android:onClick="startScan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="扫描缓存"/>
    <Button
        android:id="@+id/btn_clean"
        android:onClick="cleanCache"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="清理缓存"/>
</LinearLayout>

    <uses-permission android:name="android.permission.CLEAR_APP_CACHE"/>
    <uses-permission android:name="android.permission.GET_PACKAGE_SIZE"/>

/*
**
** Copyright 2007, 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 android.content.pm;

/**
 * API for package data change related callbacks from the Package Manager.
 * Some usage scenarios include deletion of cache directory, generate
 * statistics related to code, data, cache usage(TODO)
 * {@hide}
 */
oneway interface IPackageDataObserver {
    void onRemoveCompleted(in String packageName, boolean succeeded);
}

/*
**
** Copyright 2007, 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 android.content.pm;

import android.content.pm.PackageStats;
/**
 * API for package data change related callbacks from the Package Manager.
 * Some usage scenarios include deletion of cache directory, generate
 * statistics related to code, data, cache usage(TODO)
 * {@hide}
 */
oneway interface IPackageStatsObserver {
    
    void onGetStatsCompleted(in PackageStats pStats, boolean succeeded);
}

/* //device/java/android/android/view/WindowManager.aidl
**
** Copyright 2007, 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 android.content.pm;
parcelable PackageStats;

 　　　　//跳到系统应用信息页面
        Intent infoIntent = new Intent();
        infoIntent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
        Uri uri = Uri.fromParts("package", getPackageName(), null);//Uri.parse
        // ("package:" + mCurrentInfo.packageName);
        infoIntent.setData(uri);
        startActivity(infoIntent);