利用Andriod死亡通知机制告诉service，client被kill了

最新推荐文章于 2025-07-28 17:19:37 发布

fredhurui

最新推荐文章于 2025-07-28 17:19:37 发布

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分类专栏： Android开发文章标签： android service DeathRecipient

本文链接：https://blog.youkuaiyun.com/free555/article/details/14754323

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本文介绍了Android中使用DeathRecipient接口在不同进程间进行通讯的方法，特别是当客户端进程被kill时，服务端进程能够接收到死亡通知，从而及时释放因绑定分配的资源。通过示例代码演示了如何在客户端和服务端实现这一功能。

Android提供了一种叫做死亡通知的机制，用于满足某些应用的特定需求：

某个process需要知道另外一个process是否存活；或者当某个进程被kill的时候，另外一个进程期望知道这件事情;

一般来讲是某个bound service关心其client是否被kill

可能有人会问，为什么service会关系client是否被kill呢

应用场景：

比如：一个bound service可能会为bind过来的client分配一些资源，当client调用release或者unbind的时候则会释放资源，但是

在某个时候client确被kill了，此时如果service不知道，则为其分配的资源则不会被释放。

Android提供了一个名为DeathRecipient 的接口，

1.在client中new 一个Binder，然后传给另外一个进程，通常是一个Bound service

2.你只需在关心另外一个进程死亡信息的进程中（通常是一个service）实现DeathRecipient

3.调用client传过来的binder的linkToDeath方法

public abstract void linkToDeath (IBinder.DeathRecipient recipient, int flags)

Added in API level 1

Register the recipient for a notification if this binder goes away. If this binder object unexpectedly goes away (typically because its hosting process has been killed), then the given IBinder.DeathRecipient's DeathRecipient.binderDied() method will be called.

You will only receive death notifications for remote binders, as local binders by definition can't die without you dying as well.

Throws

RemoteException	if the target IBinder's process has already died.

public class TestActivity extends Activity {

private String TAG = "TestService";
private Button mStartBtn;
private Button mStopBtn;
private Button mBindBtn;
private Button mUnbindBtn;
ClickListener mClickListener = new ClickListener();
private Intent mIntent = new Intent("com.example.action.TEST");
private IBinder mBinder = new Binder();
private ITest mTest = null;
private ServiceConnection mServiceConnection = new ServiceConnection() {

@Override
public void onServiceDisconnected(ComponentName name) {
// TODO Auto-generated method stub
Log.d(TAG, "onServiceDisconnected");

}

@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// TODO Auto-generated method stub
Log.d(TAG, "onServiceConnected:" + name);
mTest = ITest.Stub.asInterface(service);
try {
mTest.setBinder(mBinder);
} catch (RemoteException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_service);
mStartBtn = (Button)findViewById(R.id.start);
mStopBtn = (Button)findViewById(R.id.stop);
mBindBtn = (Button)findViewById(R.id.bind);
mUnbindBtn = (Button)findViewById(R.id.unbind);
mStartBtn.setOnClickListener(mClickListener);
mStopBtn.setOnClickListener(mClickListener);
mBindBtn.setOnClickListener(mClickListener);
mUnbindBtn.setOnClickListener(mClickListener);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_test_service, menu);
return true;
}

private class ClickListener implements OnClickListener{

@Override
public void onClick(View v) {
int id = v.getId();
if(id == R.id.start){
startService(mIntent);

}else if(id == R.id.stop){
stopService(mIntent);
}else if(id == R.id.bind){
bindService(mIntent, mServiceConnection, Context.BIND_AUTO_CREATE);
}else if(id == R.id.unbind){
unbindService(mServiceConnection);
}

}

}

}

// ITest .aidl
package com.example.testservice;

/** Example service interface */
interface ITest {

int getPid();

void setBinder(IBinder client);
}

//TestService.java

public class TestService extends Service{
private String TAG = "TestService";

private TestApi mTestApi = new TestApi();

private IBinder mClient = null;

@Override
public IBinder onBind(Intent intent) {
Log.d(TAG, "Onbind() action=" + intent.getAction());
return mTestApi;
}

private class TestDeathRecipient implements DeathRecipient{

@Override
public void binderDied() {
Log.d(TAG, "client has died");
}

}

private class TestApi extends ITest.Stub{
@Override
public int getPid() throws RemoteException {
return (int)Thread.currentThread().getId();
}

@Override
public void setBinder(IBinder client) throws RemoteException {
mClient = client;
mClient.linkToDeath(new TestDeathRecipient(), 0);
}

}

}

//AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.testservice"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.testservice.TestActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

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

<service android:name="com.example.testservice.TestService"
android:process=":service">
<intent-filter>
<action android:name="com.example.action.TEST" />
</intent-filter>
</service>
</application>

</manifest>