考虑一个网页，这是显示现场游戏得分或股票的市场状况或货币汇率定量的。对于所有这些类型的页面，你需要浏览器刷新网页，定期使用referesh或重新加载“按钮。
Java Servlet的为您提供一个机制，容易在其中一个网页，它会在给定的时间间隔自动刷新。
刷新网页的最简单的方式是使用方法setIntHeader()响应对象。以下是这种方法的签名：
public void setIntHeader(String header, int headerValue)
此方法发送头“刷新”浏览器的整数值表示是以秒为单位的时间间隔。
此示例显示了，servlet如何执行自动刷新页面setIntHeader()方法来设置刷新头。
// Import required java libraries
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
// Extend HttpServlet class - by www.gitbook.net
public class Refresh extends HttpServlet {
// Method to handle GET method request.
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
// Set refresh, autoload time as 5 seconds
response.setIntHeader("Refresh", 5);
// Set response content type
response.setContentType("text/html");
// Get current time
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;
PrintWriter out = response.getWriter();
String title = "Auto Page Refresh using Servlet";
String docType =
"<!doctype html public \"-//w3c//dtd html 4.0 " +
"transitional//en\">\n";
out.println(docType +
"<html>\n" +
"<head><title>" + title + "</title></head>\n"+
"<body bgcolor=\"#f0f0f0\">\n" +
"<h1 align=\"center\">" + title + "</h1>\n" +
"<p>Current Time is: " + CT + "</p>\n");
}
// Method to handle POST method request.
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
现在让我们来编译上面的servlet在web.xml文件中创建以下条目
....
<servlet>
<servlet-name>Refresh</servlet-name>
<servlet-class>Refresh</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Refresh</servlet-name>
<url-pattern>/Refresh</url-pattern>
</servlet-mapping>
....
现在，使用URL http://localhost:8080/Refresh这将显示当前的系统时间为每5秒后调用这个servlet的。只要运行servlet看到的结果如下：
Auto Page Refresh using ServletCurrent Time is: 9:44:50 PM |