Java Timer.schedule 只运行一次

Question

我有一个基于 Timer.schedule 运行的 TiimerTask。
问题是它只在应用程序启动时运行一次...
也许这是未决的事情，但我无法理解......

这是我的类(class)，它扩展了 TimerTask

public class ClientScheduler extends TimerTask {

    public String serverUrl = Start.getHost();
    public String append = "/client/checkVersion";
    public String numeroClient = null;
    public String actualVersion = null;
    public String filePrefix = "eparkclient-";
    public String fileSuffix = "-jar-with-dependencies.jar";
    private final Logger logger = Logger.getLogger(ClientScheduler.class);

    public ClientScheduler() {

    }

    @Override
    public void run() {



                logger.debug("Scheduler starts");
                String finalUrl = null;
                try {
                     numeroClient = PropertyConfig.getClientId();

                     actualVersion = PropertyConfig.getFirmwareVersion();
                     finalUrl = serverUrl + append + "?numeroClient=" + numeroClient;

                     HttpConnection http = new HttpConnection();
                     String result = http.getHTTPResponse(finalUrl);
                     JSONObject json = new JSONObject(result);
                     String firmwareVersion = json.getString("firmwareVersion");
                     Boolean updated = json.getBoolean("firmwareUpdated");

                     if(!actualVersion.equalsIgnoreCase(firmwareVersion)){
                         //scarico il file dall'ftp
                         FTPDownload ftp = new FTPDownload();
                         String filename = filePrefix+firmwareVersion+fileSuffix;
                         logger.debug("filename è "+filename);
                        boolean success = ftp.getFile(filename);
                         if(success) {
                            //scrivo la versione nuova sul file
                             PropertyConfig.setFirmwareVersion(firmwareVersion);
                            //comunico al server l'aggiornamento riuscito
                             HttpConnection answer = new HttpConnection();
                             String url = serverUrl + "/client/pushUpdate?numeroClient=" + numeroClient + "&firmwareVersion=" +
                             firmwareVersion + "&updated=0";

                             String r = answer.getHTTPResponse(url);
                             System.exit(0);

                         }


                     } else if(actualVersion.equalsIgnoreCase(firmwareVersion) && !updated){ //ho riavviato, devo aggiornare il DB

                         HttpConnection answer = new HttpConnection();
                         String url = serverUrl + "/client/pushUpdate?numeroClient=" + numeroClient + "&firmwareVersion=" +
                         firmwareVersion + "&updated="+!updated;

                         String r = answer.getHTTPResponse(url);

                     } else {
                         logger.debug("Non dobbiamo fare niente");
                     }
                } catch (IOException e) {
                    logger.error("Errore Property", e);

                }
            }

    }

应用程序以这种方式启动时调用任务

public static void main(String[] args) throws Exception {
        logger.info("L'ip del client è " + getCurrentIP());

        //faccio partire lo scheduler
        logger.debug("Scheduler called");

        Timer timer = new Timer();
        timer.schedule(new ClientScheduler(), 10*1000);

Answer 1

您只安排计时器任务一次。

schedule 方法定义为

schedule(TimerTask task, long delay)

Schedules the specified task for execution after the specified delay.

但是你需要使用这个方法:

schedule(TimerTask task, long delay, long period)

Schedules the specified task for repeated fixed-delay execution, beginning after the specified delay.

在此处查看 Javadoc: https://docs.oracle.com/javase/8/docs/api/java/util/Timer.html#schedule-java.util.TimerTask-long-long-