ScheduledExecutorService只运行一次

Question

我希望在我启动webservice之后运行一个进程,然后每隔30分钟左右运行一次(我现在正以较小的延迟测试它,只是为了查看它是否有效),但我的进程从未运行过多次.我究竟做错了什么？

这是我的代码:

@WebListener
public class SchedulerService implements ServletContextListener{

    @Autowired
    UpdateSubscriberService updateSubscriberService;

    ScheduledExecutorService scheduledExecService;

    public SchedulerService(){
        scheduledExecService = Executors.newSingleThreadScheduledExecutor();
    }

    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        scheduledExecService.shutdown();
    }

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
        scheduledExecService.scheduleWithFixedDelay(new Runnable(){
            @Override
            public void run() {
                Date date = new Date(System.currentTimeMillis());
                System.out.println("Running scheduled update check " + date.toString());
                updateSubscriberService.checkForUpdates();
            }
        }, 60, 30, TimeUnit.SECONDS);
    }
}

Answer 1

用自动换run代码try catch

只是一个猜测:抛出异常.一个ScheduledExecutorService暂停默默地如果遇到异常.

该run方法的代码应始终由try-catch包围,以处理和吸收任何抛出的异常.

 @Override
 public void run() {
    try {  // Let no Exception reach the ScheduledExecutorService.
        Date date = new Date(System.currentTimeMillis());
        System.out.println("Running scheduled update check " + date.toString());
        updateSubscriberService.checkForUpdates();
    } catch ( Exception e ) {
        System.out.println( "ERROR - unexpected exception" );
    }
}

剔除run方法

采取婴儿步骤.从一个run除了a之外什么都不做的方法开始System.out.println.