public abstract class IntentService extends Service {     private volatile Looper mServiceLooper;     private volatile ServiceHandler mServiceHandler; //一个Handler封装了Looper对象     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) { //构造方法，需要提供一个name作为标识         super();         mName = name;     }

onStartCommand(Intent, int, int)} will return Service#START_REDELIVER_INTENT}, so if this process dies before onHandleIntent(Intent)} returns, the process will be restarted

onStartCommand(Intent, int, int)} will return Service#START_NOT_STICKY}, and if the process dies      public void setIntentRedelivery(boolean enabled) {         mRedelivery = enabled;     }     @Override     public void onCreate() { //这里重写父类Service的创建，主要是构造一个线程         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) {  //Android 2.0以前的Service启动参数控制         Message msg = mServiceHandler.obtainMessage();         msg.arg1 = startId;         msg.obj = intent;         mServiceHandler.sendMessage(msg);     }     @Override     public int onStartCommand(Intent intent, int flags, int startId) { //Android 2.0以后的服务启动参数         onStart(intent, startId);         return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;     }     @Override     public void onDestroy() { //服务摧毁的时候Looper一定要释放掉，这点很重要。         mServiceLooper.quit();     }     @Override     public IBinder onBind(Intent intent) {         return null;     }     protected abstract void onHandleIntent(Intent intent); }