问使用dev-tools重启web服务器时，计划任务不会停止

EN

@Component
public class CheckRunner implements Runnable {
    private static final Logger log = LoggerFactory.getLogger(CheckRunner.class);

    private static boolean runOnce = true;

    private final long DEFAULT_CHECKING_INITIAL = 1L;
    private final long DEFAULT_CHECKING_PERIOD = 10L;

    @Autowired
    public EmailServiceImpl emailService;

    /**
     * Construct and schedule a CheckRunner 
     */
    public CheckRunner() {
        if(runOnce) {
            runOnce = false;
            log.info("Starting check runner.");
            ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor();
            exec.scheduleAtFixedRate(this, DEFAULT_CHECKING_INITIAL , DEFAULT_CHECKING_PERIOD, TimeUnit.MINUTES);
        }
    }

    /**
     * Run the checks once
     */
    @Override
    public void run() {
        log.info("Checking thread running.");
        checks();
    }

    /**
     * Do the checks
     */
    private void checks() {
        StringBuilder sb = new StringBuilder();
        //sb.append("<pre>");
        WebServerAvailablityCheck.runAllChecks(sb, emailService);
        //sb.append("</pre>");
    }

}