我们都知道在Android的设置->应用程序中可以查看应用程序的相关信息，其中有一个功能是清除缓存。如图：

怎么实现这些功能呢，从Android的setting源码中可以得到相关信息。

实现如下：

Java代码：

package com.wang.clearcache;

import java.lang.reflect.Method;

import android.os.Bundle;

import android.os.RemoteException;

import android.app.Activity;

import android.content.pm.IPackageStatsObserver;

import android.content.pm.PackageManager;

import android.content.pm.PackageStats;

public class MainActivity extends Activity {

private PackageManager pm;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

pm = getPackageManager();

//反射

try {

Method method = PackageManager.class.getMethod("getPackageSizeInfo", new Class[]{String.class,IPackageStatsObserver.class});

method.invoke(pm, new Object[]{"com.wang.clearcache",new IPackageStatsObserver.Stub() {

@Override

public void onGetStatsCompleted(PackageStats pStats, boolean succeeded)

throws RemoteException

{

long cachesize = pStats.cacheSize;

long codesize = pStats.codeSize;

long datasize = pStats.dataSize;

System.out.println("cachesize:"+ cachesize);

System.out.println("codesize:"+ codesize);

System.out.println("datasize"+ datasize);

}

}});

} catch (Exception e) {

e.printStackTrace();

}

}

}

因为得到缓存信息需要加入android.permission.GET_PACKAGE_SIZE的权限 Androidmainifest.xml

package="com.wang.clearcache"

android:versionCode="1"

android:versionName="1.0" >

android:minSdkVersion="8"

android:targetSdkVersion="17" />

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

android:name="com.wang.clearcache.MainActivity"

android:label="@string/app_name" >

因为使用在代码中使用了PackageManager的getPackageSizeInfo这个函数，但是这个方法是不对外公开的函数，所有我们需要使用发射来调用这个函数，在该方法的内部回调了onGetStatsCompleted(PackageStats pStats, boolean succeeded)这个方法，通过该方法的pStats参数可以得到应用的缓存，数据缓存，代码容量缓存，在使用的过程中需要用到系统的aidl文件

IPackageStatsObserver：

/*

**

** 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);

}

PackageStats：

/* //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;

最后运行的结果：

源码地址下载：