使用延迟队列处理超时订单
延迟队列是一种更为高效和可控的方式来处理定时任务，特别是在需要处理超时订单这类场景时。延迟队列可以让你将任务按照延迟时间有序地执行，而不需要通过轮询的方式频繁地检查订单表。
在Java中，可以使用Delayed接口和DelayQueue来实现延迟队列。以下是一个基于延迟队列的实时订单自动取消的示例：
- 定义延迟任务类：
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;public class DelayedOrderCancellation implements Delayed {private final Order order;private final long delayTime; // 延迟时间public DelayedOrderCancellation(Order order, long delayTime) {this.order = order;this.delayTime = System.currentTimeMillis() + delayTime;}public Order getOrder() {return order;}@Overridepublic long getDelay(TimeUnit unit) {return unit.convert(delayTime - System.currentTimeMillis(), TimeUnit.MILLISECONDS);}@Overridepublic int compareTo(Delayed o) {return Long.compare(this.delayTime, ((DelayedOrderCancellation) o).delayTime);}
}
- 使用延迟队列执行任务：
import java.util.concurrent.DelayQueue;public class OrderCancellationManager {private final DelayQueue<DelayedOrderCancellation> delayQueue = new DelayQueue<>();public void scheduleOrderCancellation(Order order, long delayTime) {DelayedOrderCancellation delayedOrderCancellation = new DelayedOrderCancellation(order, delayTime);delayQueue.put(delayedOrderCancellation);}public void startOrderCancellationScheduler() {new Thread(() -> {while (true) {try {DelayedOrderCancellation delayedOrderCancellation = delayQueue.take();processOrderCancellation(delayedOrderCancellation.getOrder());} catch (InterruptedException e) {Thread.currentThread().interrupt();}}}).start();}private void processOrderCancellation(Order order) {// 处理订单取消逻辑// ...}
}
- 使用示例：
public class Main {public static void main(String[] args) {OrderCancellationManager orderCancellationManager = new OrderCancellationManager();orderCancellationManager.startOrderCancellationScheduler();// 在创建订单时调用Order order = createOrder();orderCancellationManager.scheduleOrderCancellation(order, TimeUnit.MINUTES.toMillis(30));}private static Order createOrder() {// 创建订单的逻辑// ...}
}
在这个示例中，DelayedOrderCancellation实现了Delayed接口，它会根据订单的延迟时间在延迟队列中排序。OrderCancellationManager负责将订单加入延迟队列，并通过单独的线程处理延迟队列中到期的任务，执行订单取消逻辑。
使用延迟队列的好处在于避免了频繁的轮询，使得系统更加高效。同时，通过设置合适的延迟时间，可以更灵活地控制任务的执行时间。