我们都知道在Android的设置->应用程序中能够查看应用程序的相关信息，当中有一个功能是清除缓存。

如图：

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怎么实现这些功能呢，从Android的setting源代码中能够得到相关信息。

实现例如以下：

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();

		}

	}

}

由于得到缓存信息须要增加android.permission.GET_PACKAGE_SIZE的权限

Androidmainifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.wang.clearcache"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="17" />

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

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

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

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>

</pre><pre name="code" class="java">

由于使用在代码中使用了PackageManager的getPackageSizeInfo这个函数。可是这种方法是不正确外公开的函数，全部我们须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)这种方法，通过该方法的pStats參数能够得到应用的缓存，数据缓存，代码容量缓存，在使用的过程中须要用到系统的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;

最后执行的结果：

源代码地址下载：

http://download.csdn.net/detail/wangbiaohome/8026535