Android:无法使用 Android 服务重复执行任务

Question

我在 android 中编写了一个服务。我想使用服务重复执行一个任务。那就是服务不应该死，应该重复执行任务。然而，该服务只执行一次任务，然后被杀死。如何在后台重复执行任务。我现在的代码是->

public class SyncService extends Service {

    private Looper mServiceLooper;
    private ServiceHandler mServiceHandler;


    @Override
    public void onCreate() {
// Start up the thread running the service.  Note that we create a
// separate thread because the service normally runs in the process's
// main thread, which we don't want to block.  We also make it
// background priority so CPU-intensive work will not disrupt our UI.
        HandlerThread thread = new HandlerThread("ServiceStartArguments", Process.THREAD_PRIORITY_BACKGROUND);
        thread.start();

// Get the HandlerThread's Looper and use it for our Handler
        mServiceLooper = thread.getLooper();
        mServiceHandler = new ServiceHandler(mServiceLooper);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Toast.makeText(SyncService.this, "servicestarting", Toast.LENGTH_SHORT).show();


        Message msg = mServiceHandler.obtainMessage();
        msg.arg1 = startId;
        mServiceHandler.sendMessage(msg);

        // If we get killed, after returning from here, restart
        return START_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        // We don't provide binding, so return null
        return null;
    }

    @Override
    public void onDestroy() {
        Toast.makeText(SyncService.this, "service done", Toast.LENGTH_SHORT).show();
    }

    // Handler that receives messages from the thread
    private final class ServiceHandler extends Handler {
        public ServiceHandler(Looper looper) {
            super(looper);
        }

        @Override
        public void handleMessage(Message msg) {
        Toast.makeText(SyncService.this, "repeatedly perform some task", Toast.LENGTH_SHORT).show();

        //constantly perform task here

        }
    }
}

如何使用服务重复执行某项任务？

Answer 1

好吧，您只向 Handler 发送一条消息。因此该消息将被处理一次。您可以让 Handler 再次传回相同的消息，但没有延迟这不是一个好主意——您会死锁主线程。重复做某事的最佳方式是分离出一个 Thread 并在 Thread 中执行它，并且 Thread 的 Runnable 永远循环。