<!DOCTYPE html>
<html>
<head>
<title>index.html</title>
<meta name="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<h2 id="tt"></h2>
<script>
function i(id){
return document.getElementById(id);
}
var ajax=new XMLHttpRequest;
ajax.onreadystatechange=ok;
function ok(){
if(ajax.status==200&&ajax.readyState==4){
i('tt').innerHTML=ajax.responseText;
}
}
function aa(){
ajax.open("post","timer");
ajax.send(null);
}
aa();
setInterval(aa,1000);
</script>
</body>
</html>
package web11_ajax.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/timer")
public class Timer extends HttpServlet{
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
String timer=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
PrintWriter out=response.getWriter();
out.print(timer);
out.close();
}
}
