JSP Auto Refresh

Imagine if you want to live broadcast match scores, the real-time status of the stock market, or the current foreign exchange rates, how would you implement it? Obviously, to achieve such real-time functionality, you have to refresh the page regularly.

JSP provides a mechanism to make this work easy; it can automatically refresh the page on a timed basis.

The simplest way to refresh a page is to use the setIntHeader() method of the response object. The signature of this method is as follows:

public void setIntHeader(String header, int headerValue)

This method notifies the browser to refresh after a given time, with the time in seconds.

Page Auto Refresh Program Example

This example uses the setIntHeader() method to set the refresh header, simulating a digital clock:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.io.*,java.util.*" %>
<html>
<head>
<title>自动刷新实例</title>
</head>
<body>

<h2>自动刷新实</h2>
<%
   // 设置每隔5秒刷新一次
   response.setIntHeader("Refresh", 5);
   // 获取当前时间
   Calendar calendar = new GregorianCalendar();
   String am_pm;
   int hour = calendar.get(Calendar.HOUR);
   int minute = calendar.get(Calendar.MINUTE);
   int second = calendar.get(Calendar.SECOND);
   if(calendar.get(Calendar.AM_PM) == 0)
      am_pm = "AM";
   else
      am_pm = "PM";
   String CT = hour+":"+ minute +":"+ second +" "+ am_pm;
   out.println("当前时间为: " + CT + "\n");
%>

</body>
</html>

Save the above code in the main.jsp file and access it. It will refresh the page every 5 seconds and obtain the system's current time. The results are as follows:

自动刷新实

当前时间为: 6:5:36 PM

You can also write a more complex program yourself.

Other Extensions