吴小龙同學

Android之Service

使用清单文件声明服务

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<manifest ... >
...
<application ... >
<service android:name=".HelloService" />
...
</application>
</manifest>

管理服务生命周期

  • 启动的服务
    startService()->onCreate()->onStartCommand()->running->stopService()/stopSelf()->onDestroy()->stopped 其中,服务未运行时会调用一次onCreate(),运行时不调用。
  • 绑定的服务
    bindService()->onCreate()->onBind()->running->onUnbind()->onDestroy()->stopped

代码示例

xml

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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/start_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Start Service" />
<Button
android:id="@+id/stop_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Stop Service" />
<Button
android:id="@+id/bind_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Stop Service" />
<Button
android:id="@+id/unbind_service"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Stop Service" />
</LinearLayout>

java

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public class HelloServiceActivity extends AppCompatActivity {
HelloService.HelloBinder mBinder;
//Service和Activity通信
private ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
mBinder = (HelloService.HelloBinder) service;
mBinder.startDownload();
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hello_service);
findViewById(R.id.start_service).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(), HelloService.class);
startService(intent);
}
});
findViewById(R.id.stop_service).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(), HelloService.class);
stopService(intent);
}
});
findViewById(R.id.bind_service).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//调用者与服务绑定在了一起,调用者一旦退出,服务也就终止
Intent intent = new Intent(getApplicationContext(), HelloService.class);
bindService(intent, serviceConnection, BIND_AUTO_CREATE);
}
});
findViewById(R.id.unbind_service).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//让Service和Activity解除关联
unbindService(serviceConnection);
}
});
}
}

HelloService

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public class HelloService extends Service {
int mStartMode; // indicates how to behave if the service is killed
// IBinder mBinder; // interface for clients that bind
boolean mAllowRebind; // indicates whether onRebind should be used
private HelloBinder mBinder = new HelloBinder();
@Override
public void onCreate() {
// The service is being created
Log.d("wxl", "HelloService onCreate");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// The service is starting, due to a call to startService()
Log.d("wxl", "HelloService onStartCommand");
flags = START_STICKY;
return super.onStartCommand(intent, flags, startId);
}
@Override
public IBinder onBind(Intent intent) {
// A client is binding to the service with bindService()
Log.d("wxl", "HelloService onBind");
return mBinder;
}
@Override
public boolean onUnbind(Intent intent) {
// All clients have unbound with unbindService()
Log.d("wxl", "HelloService onUnbind");
return mAllowRebind;
}
@Override
public void onRebind(Intent intent) {
// A client is binding to the service with bindService(),
// after onUnbind() has already been called
Log.d("wxl", "HelloService onRebind");
}
public class HelloBinder extends Binder {
public void startDownload() {
Log.d("wxl", "HelloService startDownload() executed");
// 执行具体的下载任务
}
}
@Override
public void onDestroy() {
// The service is no longer used and is being destroyed
Log.d("wxl", "HelloService onDestroy");
Intent intent = new Intent(this, HelloService.class);
startService(intent);
}
}

Service KILL问题

  • settings 中stop service
    onDestroy方法中,调用startService进行Service的重启。
  • settings中force stop 应用
    未解决
  • 借助第三方应用kill掉running task
    未解决

附录

官方Service API指南
Android Service完全解析,关于服务你所需知道的一切(上)
Service服务详解以及如何使service服务不被杀死


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