java - 具有可变延迟的 ScheduledExecutorService

Question

假设我有一个任务是从 java.util.concurrent.BlockingQueue 中提取元素并处理它们。

public void scheduleTask(int delay, TimeUnit timeUnit)
{
    scheduledExecutorService.scheduleWithFixedDelay(new Task(queue), 0, delay, timeUnit);
}

如果可以动态更改频率，我如何安排/重新安排任务？

• 这个想法是获取数据更新流并将它们批量传播到 GUI
• 用户应该能够改变更新频率

Answer 1

使用 schedule(Callable<V>, long, TimeUnit)而不是 scheduleAtFixedRate或 scheduleWithFixedDelay .然后确保您的 Callable 在未来的某个时间重新安排自身或新的 Callable 实例。例如:

// Create Callable instance to schedule.
Callable<Void> c = new Callable<Void>() {
  public Void call() {
   try { 
     // Do work.
   } finally {
     // Reschedule in new Callable, typically with a delay based on the result
     // of this Callable.  In this example the Callable is stateless so we
     // simply reschedule passing a reference to this.
     service.schedule(this, 5000L, TimeUnit.MILLISECONDS);
   }  
   return null;
  }
}

service.schedule(c);

这种方法无需关闭并重新创建 ScheduledExecutorService .