Java Timer.schedule仅运行一次

Question

我有一个TimerTask，它应该基于Timer.schedule运行。

问题是当应用程序启动时它只运行一次...

也许有什么事情还未完成，但我无法理解是什么...

这是我的扩展TimerTask的类：

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);

                }
            }

    }

这个任务被称为当应用程序以这种方式启动时触发。

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);

- MarioC

---

你有阅读文档吗？你需要调用一个带有三个参数的schedule方法来实现重复执行。 - VGR

Answer 1

只需一次调度计时器任务。

schedule方法定义为

schedule(TimerTask task, long delay)

在指定的延迟之后安排要执行的指定任务。

但是您需要使用此方法：

schedule(TimerTask task, long delay, long period)

安排指定任务进行重复的固定延迟执行，开始于指定的延迟之后。

请参见此处的Javadocs：https://docs.oracle.com/javase/8/docs/api/java/util/Timer.html#schedule-java.util.TimerTask-long-long-

- thst