Tape队列相关的Java类

Tape 是一组跟队列相关的工具类，同时也适用于 Android 平台。

示例代码：

/** Listener for starting the upload service when the queue has tasks. */

public class ImageQueueServiceListener implements ObjectQueue.Listener<ImageUploadTask> {

  private final Context context;



  public ImageQueueServiceStarter(Context context) {

    this.context = context;

  }



  @Override public void onAdd(ObjectQueue<ImageUploadTask>, ImageUploadTask task) {

    context.startService(new Intent(context, ImageQueueService.class));

  }



  @Override public void onRemove(ObjectQueue<ImageUploadTask>) {}

}



/** Service which iterates through pending upload tasks one-by-one. */

public class ImageQueueService extends Service implements ImageUploadTask.Callback {

  private TaskQueue<ImageUploadTask> queue;

  private boolean running;



  @Override public void onCreate() {

    super.onCreate();

    // Obtain TaskQueue here (e.g., through injection)

  }



  @Override public int onStartCommand(Intent intent, int flags, int startId) {

    executeNext();

    return START_STICKY;

  }



  public void executeNext() {

    if (running) return; // Only one task at a time.

    ImageUploadTask task = queue.peek();

    if (task != null) {

      task.execute(this);

      running = true;

      return;

    }

    stopSelf(); // We're done for now.

  }



  @Override public void imageUploadComplete() {

    running = false;

    queue.remove();

    executeNext();

  }

}