IntentService解析

IntentService中内置了一个HandlerThread，能够对数据进行处理。相比于普通的Service，IntentService有以下优点：

1. 不用在Service创建线程。

2. 不用考虑什么时候关闭Service。

IntentService使用示例

CountService类

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package com.fxb.intentservicetest;   import android.app.IntentService; import android.content.Intent; import android.util.Log;   public class CountService extends IntentService{       private volatile boolean isRunning = true;       public CountService(String name) {         super(name);     }       public CountService(){         super("CountService");     }       @Override     protected void onHandleIntent(Intent intent) {         Log.i(MainActivity.TAG, "StartCount");         int count = intent.getIntExtra("StartCount", 0);         startCount(count);       }       private void startCount(int count){         isRunning = true;         while(isRunning){             try {                 Thread.sleep(1000);             } catch (InterruptedException e) {                 e.printStackTrace();             }               count++;             Intent intent = new Intent("MY_COUNTER");             intent.putExtra("count", count);             sendBroadcast(intent);         }     }     }

测试Activity

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package com.fxb.intentservicetest;   import android.app.Activity; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.TextView;   public class MainActivity extends Activity implements View.OnClickListener{       public static final String TAG = "IntentServiceTest";       private TextView tvShow;     private Button btnStart;     private BroadcastReceiver receiver;       @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         initView();           receiver = new BroadcastReceiver() {             @Override             public void onReceive(Context context, Intent intent) {                 int count = intent.getIntExtra("count", 0);                 tvShow.setText("count:"+count);             }         };         IntentFilter filter = new IntentFilter();         filter.addAction("MY_COUNTER");         registerReceiver(receiver, filter);     }       private void initView(){         tvShow = (TextView)findViewById(R.id.tvShow);         btnStart = (Button)findViewById(R.id.btnStart);           btnStart.setOnClickListener(this);     }       @Override     public void onClick(View v) {         if(v == btnStart){             Intent intent = new Intent(this, CountService.class);             intent.putExtra("StartCount", 5);             startService(intent);               Log.i(MainActivity.TAG, "my click");         }     }       @Override     protected void onDestroy() {         super.onDestroy();         unregisterReceiver(receiver);     } }

点击Start按钮后，tvShow依次递增变化，从5开始。

 

IntentService源码

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package android.app;   import android.content.Intent; import android.os.Handler; import android.os.HandlerThread; import android.os.IBinder; import android.os.Looper; import android.os.Message;   public abstract class IntentService extends Service {     private volatile Looper mServiceLooper;     private volatile ServiceHandler mServiceHandler;     private String mName;     private boolean mRedelivery;       private final class ServiceHandler extends Handler {         public ServiceHandler(Looper looper) {             super(looper);         }           @Override         public void handleMessage(Message msg) {             onHandleIntent((Intent)msg.obj);             stopSelf(msg.arg1);         }     }       public IntentService(String name) {         super();         mName = name;     }       public void setIntentRedelivery(boolean enabled) {         mRedelivery = enabled;     }       @Override     public void onCreate() {         // TODO: It would be nice to have an option to hold a partial wakelock         // during processing, and to have a static startService(Context, Intent)         // method that would launch the service & hand off a wakelock.           super.onCreate();         HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");         thread.start();           mServiceLooper = thread.getLooper();         mServiceHandler = new ServiceHandler(mServiceLooper);     }       @Override     public void onStart(Intent intent, int startId) {         Message msg = mServiceHandler.obtainMessage();         msg.arg1 = startId;         msg.obj = intent;         mServiceHandler.sendMessage(msg);     }       @Override     public int onStartCommand(Intent intent, int flags, int startId) {         onStart(intent, startId);         return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;     }       @Override     public void onDestroy() {         mServiceLooper.quit();     }       @Override     public IBinder onBind(Intent intent) {         return null;     }       protected abstract void onHandleIntent(Intent intent); }