Java DeferredTask类代码示例

import com.google.appengine.api.taskqueue.DeferredTask; //导入依赖的package包/类
private static void deferredTask(HttpServletRequest req, HttpServletResponse resp)
    throws IOException {
  String queue = req.getParameter("queue");
  Queue q;
  if (queue == null) {
    q = QueueFactory.getDefaultQueue();
  } else {
    q = QueueFactory.getQueue(queue);
  }
  final String data = req.getParameter("deferredData");

  TaskOptions opts =
      TaskOptions.Builder.withPayload(
          new DeferredTask() {
            @Override
            public void run() {
              gotCalledBack(data);
            }
          });

  latch = new CountDownLatch(1);
  TaskHandle handle = q.add(opts);
  resp.getWriter().print(handle.getQueueName());
}
 

import com.google.appengine.api.taskqueue.DeferredTask; //导入依赖的package包/类
private static DeferredTask newDeferredTask(Constructor<DeferredTask> ctor, Object arg) {
  try {
    return ctor.newInstance(arg);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}
 

import com.google.appengine.api.taskqueue.DeferredTask; //导入依赖的package包/类
/**
 * Publishes messages to clients listening on an object.
 */
public void publishMessages(ObjectId object, String jsonString) {
  for (Platform platform : Platform.values()) {
    DeferredTask notify = new PushNotify(object.toString(), jsonString, platform);
    QUEUE.add(TaskOptions.Builder.withPayload(notify));
  }
  log.info("Scheduled push notifications: " + object + " " + jsonString);
}
 

import com.google.appengine.api.taskqueue.DeferredTask; //导入依赖的package包/类
public static void scheduleRequest(RideRequest rideRequest) {
    DeferredTask task = new SendNotificationTask(rideRequest.getId());
    QueueFactory.getQueue(QUEUE_NAME).add(TaskOptions.Builder.withPayload(task));
}
 

import com.google.appengine.api.taskqueue.DeferredTask; //导入依赖的package包/类
@Override
public void run() {
    if(event == null || eventHandlers.isEmpty())
        return;

    String key = event.getClass().getName();

    if(!eventHandlers.containsKey(key))
        return;

    List<Class<? extends EventHandler<? extends Event>>> handlersForType = eventHandlers.get(key);

    List<DeferredTask> taskList = new ArrayList<DeferredTask>();

    /*
     * Loop through all of the event handlers for the event being published 
     * and attempt to instantiate the handlers through reflection.
     */
    for(Class<? extends EventHandler<? extends Event>> handler : handlersForType){

        try{
            /*
             * get a constructor that expects a single parameter value that matches the event's type
             */
            Constructor<? extends EventHandler<? extends Event>> constructor = handler.getDeclaredConstructor(event.getClass());
            constructor.setAccessible(true);
            taskList.add(constructor.newInstance(event));

        } catch (NoSuchMethodException | SecurityException | InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
            /*
             * unable to create an instance of the handler.
             * more than likely this is caused by the handler
             * not implementing a constructor that takes a single
             * parameter instance of the event.
             * 
             *  There are several possibilities for this situation
             *  - Publish a new event
             *  - Log the exception
             *  - Send an email to an administrator
             *  - etc..
             */
        }
    }

    if(taskList.isEmpty())
        return;

    Queue taskQueue = null;

    if(queue != null)
        taskQueue = QueueFactory.getQueue(queue);
    else
        taskQueue = QueueFactory.getDefaultQueue();

    for(DeferredTask task : taskList){
        taskQueue.addAsync(TaskOptions.Builder.withPayload(task));
    }
}