如何在Java中創建一個線程每隔5秒運行一次后台

Question

如果值超過閾值，我有一個代碼可以創建警報，並希望該代碼每5秒在后台運行一次。

這是我的代碼：

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String Name = request.getParameter("alarmName");
    String Description = request.getParameter("desc");
    String Metric = request.getParameter("name");
    String threshold = request.getParameter("threshold");
    String sign = request.getParameter("sign");

     response.setContentType("text/html");
        PrintWriter out = response.getWriter();
       // List<String> lst = new ArrayList<String>();
        System.out.println("Hello" +Name);
        System.out.println(Description);
        System.out.println(Metric);
        System.out.println(threshold);
        System.out.println(sign);


        try
    {
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","123");
        PreparedStatement ps = con.prepareStatement("Insert into alarmdetails(Name, Description, Metric, threshold,sign) values(?,?,?,?,?)");
        System.out.println(ps);
        ps.setString(1,Name);
        ps.setString(2,Description);
        ps.setString(3,Metric);
        ps.setString(4,threshold);
        ps.setString(5,sign);
        ps.executeUpdate();   

        if(Metric.equals("cpuUsage"))
        {   
            if(sign.equals("greaterthan"))
            {
                System.out.println("reached here3");
                PreparedStatement ps1 = con.prepareStatement("select CPU_USAGE from metrics WHERE CPU_USAGE > (SELECT threshold from alarmdetails WHERE Name='"+Name+"')");
                ResultSet rs1 = ps1.executeQuery();

                if(rs1.next())
                {
                    System.out.println("Alert, CPU Usage greater than threshold");
                }
                else
                {
                    System.out.println("All good");
                }
            }
        } catch (Exception e)
        {
        System.out.println(e);
        }

        String url = "Homepage.jsp";

        RequestDispatcher dispatcher = request.getRequestDispatcher(url);
        dispatcher.forward(request, response);

      }

      }

我想從if(Metric.equals(cpuUsage))....在每5秒運行一次的線程中運行代碼。

我以前從未實現過線程，因此不勝感激。 謝謝。

Answer 1

嘗試在指定的Delay上使用ScheduledExecutorService。

ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor();
executorService.scheduleWithFixedDelay(new MyRunnable(), 0, 5, TimeUnit.SECONDS);

在這里，MyRunnable類將實現Runnable，並且它的run方法將具有您的處理代碼，而無需擔心時間延遲。