android IntentService实现原理及内部代码分享

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);
}