Android 之Service

　　service是运行在后台的服务,你可以启动一个服务Service来播放音乐，或者记录你地理信息位置的改变，或者启动一个服务来运行并一直监听某种动作。

接下来分析一下service 的生命周期：

1：actiivty_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button 
        android:id="@+id/btn_bind_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Bind Service"/>
    
    <Button 
        android:id="@+id/btn_stop_bind"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/btn_bind_service"
        android:text="Stop Bind"/>
    
    <Button 
        android:id="@+id/btn_start_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/btn_stop_bind"
        android:text="Start Service"/>
    
    <Button 
        android:id="@+id/btn_stop_service"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/btn_start_service"
        android:text="Stop Service"/>
</RelativeLayout>

2:ServiceDemo.java

public class ServiceDemo extends Service{
    private static final String TAG="ServiceDemo";
    public static final String ACTION="com.yan.service.ServiceDemo";
    
    @Override
    public IBinder onBind(Intent arg0) {
        Log.i(TAG, "onBind");
        return null;
    }

    @Override
    public void onCreate() {
        Log.i(TAG,"onCreate");
        super.onCreate();
    }

    @Override
    @Deprecated
    public void onStart(Intent intent, int startId) {
        Log.i(TAG, "onStart");
        super.onStart(intent, startId);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i(TAG, "onStartCommand");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        Log.i(TAG, "onDestroy");
        super.onDestroy();
    }

    @Override
    public boolean onUnbind(Intent intent) {
        Log.i(TAG, "onUnbind");
        return super.onUnbind(intent);
    }
}

3:MainActivity.java

public class MainActivity extends Activity {
    private Button btnBindService=null;
    private Button btnStopBind=null;
    private Button btnStartService=null;
    private Button btnStopService=null;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        btnBindService=(Button)findViewById(R.id.btn_bind_service);
        btnStopBind=(Button)findViewById(R.id.btn_stop_bind);
        btnStartService=(Button)findViewById(R.id.btn_start_service);
        btnStopService=(Button)findViewById(R.id.btn_stop_service);
        
        btnBindService.setOnClickListener(new OnClickListener(){
            public void onClick(View view){
                Intent intent=new Intent(ServiceDemo.ACTION);
                bindService(intent,sc,BIND_AUTO_CREATE);
            }
        });
        
        btnStopBind.setOnClickListener(new OnClickListener(){
            public void onClick(View view){
                unbindService(sc);
            }
        });
        
        btnStartService.setOnClickListener(new OnClickListener(){
            public void onClick(View view){
                Intent intent=new Intent(ServiceDemo.ACTION);
                startService(intent);
            }
        });
        
        
        btnStopService.setOnClickListener(new OnClickListener(){
            public void onClick(View view){
                Intent intent=new Intent(ServiceDemo.ACTION);
                stopService(intent);
            }
        });
    }

    ServiceConnection sc=new ServiceConnection(){
        @Override
        public void onServiceConnected(ComponentName arg0, IBinder arg1) {
            Log.i("SC", "onServiceConnected");
        }
        @Override
        public void onServiceDisconnected(ComponentName arg0) {
            Log.i("SC", "onServiceDisconnected");
        }
    };
}

4:AndroidManifest.xml

<service 
            android:name="com.yan.service.ServiceDemo">
            <intent-filter>
                <action android:name="com.yan.service.ServiceDemo"/>
            </intent-filter>
        </service>

5:运行结果分析。

（1）点击StartService:

执行 onCreate()->onStartCommand()->onStart()

（2）点击StopService:

执行 onDestroy()

（3）点击BindService

执行 onCreate()->onBind()

（4）点击StopBind

执行 onUnbind()->onDestory()