ajax+servlet 简易时间效果

时间：2022-05-22 10:32:13
<!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();

    }

}

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