java - 如何在Java中的方法中设置超时并在一段时间内重试方法

Question

我编写了一个 java 方法，它连接到 Web 服务。有时这种方法需要很长时间才能建立连接。我想要例如它需要超过 5 秒，然后停止当前程序并重新启动 3 次以上。如果所有时间都失败，则完全中止。

到目前为止，我已经写了以下内容:

        private ConnectionInterface  connectWithTimeout() throws MalformedURLException, Exception {

        ExecutorService executor = Executors.newCachedThreadPool();
        Callable<Object> task = new Callable<Object>() {
            public Object call() throws InterruptedException, MalformedURLException, Exception {
                return connectWithNoTimeout();  //This is the method that takes to long. If this method takes more than 5 seconds, I want to cancel and retry for 3 more times. Then abort completely.
            }
        };
        Future<Object> future = executor.submit(task);
        try {
            Object result = future.get(5, TimeUnit.SECONDS);
        } catch (TimeoutException ex) {

            System.out.println( "Timeout Occured");

        } catch (InterruptedException e) {
          System.out.println( " "InterruptedException Occured");


        } catch (ExecutionException e) {
            System.out.println( ""ExecutionException Occured");


        } finally {

            future.cancel(true); // here the method gets canceled. How do I retry it?
        }
        System.out.println( "Connected !!");
        return connectWithNoTimeout();
}



private ConnectionInterface  connectWithNoTimeout() throws MalformedURLException, Exception {}

Answer 1

您的方法已经有 5 秒超时。您现在需要做的就是添加某种具有 3 次重复的循环。您需要超时计数器和成功尝试后的休息时间。不确定发生其他异常时您想做什么，也在那里添加了中断。以下代码应该可以完成这项工作:

private ConnectionInterface  connectWithTimeout() throws MalformedURLException, Exception {
        int repeatCount = 0;

        ExecutorService executor = Executors.newCachedThreadPool();
        Callable<Object> task = new Callable<Object>() {
            public Object call() throws InterruptedException, MalformedURLException, Exception {
                return connectWithNoTimeout();  //This is the method that takes to long. If this method takes more than 5 seconds, I want to cancel and retry for 3 more times. Then abort completely.
            }
        };

        while (repeatCount < 3){
          Future<Object> future = executor.submit(task);
          try {
              Object result = future.get(5, TimeUnit.SECONDS);
              break;

          } catch (TimeoutException ex) {
            repeatCount++;
            System.out.println( "Timeout Occured");

          } catch (InterruptedException e) {
            System.out.println( " "InterruptedException Occured");
            break; 

          } catch (ExecutionException e) {
              System.out.println( "ExecutionException Occured");
            break;    

          } finally {

              future.cancel(true); // here the method gets canceled. How do I retry it?
          }
        }
        System.out.println( "Connected !!");
        return connectWithNoTimeout();
    }