IntentService

HandlerThread和Handler實現(xiàn)異步操作

• 它本質是一種特殊的Service峭范，繼承自Service并且本身就是一個抽象類。
• 它內部通過HandlerThread和Handler實現(xiàn)異步操作。
• 當任務執(zhí)行完后，IntentService會自動停止.
• 可以啟動IntentService多次租冠，而每一次耗時操作會以工作隊列的方式在IntentService的onHandleIntent回調方法中執(zhí)行，并且薯嗤，每次只會執(zhí)行一個工作線程顽爹，執(zhí)行完第一個再執(zhí)行第二個。

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() {
        super.onCreate();
        HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");
        thread.start();

        mServiceLooper = thread.getLooper();
        mServiceHandler = new ServiceHandler(mServiceLooper);
    }

    @Override
    public void onStart(@Nullable Intent intent, int startId) {
        Message msg = mServiceHandler.obtainMessage();
        msg.arg1 = startId;
        msg.obj = intent;
        mServiceHandler.sendMessage(msg);
    }

    @Override
    public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
        onStart(intent, startId);
        return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;
    }

    @Override
    public void onDestroy() {
        mServiceLooper.quit();
    }

    @Override
    @Nullable
    public IBinder onBind(Intent intent) {
        return null;
    }

    @WorkerThread
    protected abstract void onHandleIntent(@Nullable Intent intent);
}