ajax学习-优快云博客

本文介绍了一种通过Ajax技术实现网页与服务器异步交互的方法。利用JavaScript创建XMLHttpRequest对象，向服务器发起GET请求，并根据服务器响应更新页面内容。演示了如何在用户操作后不刷新页面的情况下获取并显示来自服务器的数据。

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package com.isvi.web.servlet;


import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AjaxServlet extends HttpServlet {

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("print ajax");
		PrintWriter pw=resp.getWriter();
		pw.println("ajax request");
		pw.flush();
		pw.close();
	}
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>ajaxTest.html</title>
	
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
	<script type="text/javascript"><!--
var currentHttp;
function ajaxFunction()
 {
 try
    {
   // Firefox, Opera 8.0+, Safari
    xmlHttp=new XMLHttpRequest();
    }
 catch (e)
    {

  // Internet Explorer
   try
      {
      xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
      }
   catch (e)
      {

      try
         {
         xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
         }
      catch (e)
         {
         alert("您的浏览器不支持AJAX！");
         return false;
         }
      }
    }
   return xmlHttp;
 }
 function sendMessage(){
 	alert("send")  
 	var xmlHttp=ajaxFunction();
 	currentHttp=xmlHttp;
 	alert(xmlHttp);
 	var url="http://localhost:8080/WebStrutsGuoDeGang/servlet/AjaxServlet";
 	xmlHttp.onreadystatechange=stateChanged;
 	xmlHttp.open("GET",url,true);
 	xmlHttp.send(null);
 }
 function stateChanged(){
 	
 	
 	if (currentHttp.readyState==4){
 		alert(currentHttp.responseText);
 	}
 }
 
--></script>
  </head>
  <html>
<body>

<form name="myForm">
用户: <input type="text" name="username" />
时间: <input type="text" name="time" />
     <input type="button" οnclick="sendMessage()"> 
</form></body>
</html>

 }