ajax学习笔记一

1.新建工程ajax_demo01

2.在src下面新建一个包com.ajax.test并在这个包下新建一个servlet

   AjaxTest.java

  

package com.ajax.test;

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 AjaxTest extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request,response);

	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		String name=request.getParameter("name");
		if(name!=null)
		{
			out.println("error");
		}else
		{
			out.println("success");
		}
	}

}

 

然后在WebRoot下面新建一个文件夹js在这个文件夹新建一个文件

    verify.js

   

   

		var req; //定义变量,用来创建xmlhttprequest对象
        function creatReq() // 创建xmlhttprequest,ajax开始
        {
           // var url="servlet/AjaxTest"; //要请求的服务端地址
            if(window.XMLHttpRequest) //非IE浏览器,用xmlhttprequest对象创建
            {
                req=new XMLHttpRequest();
            }
            else if(window.ActiveXObject) //IE浏览器用activexobject对象创建
            {
                req=new ActiveXObject("Microsoft.XMLHttp");
            }
            
            if(req) //成功创建xmlhttprequest
            {
            	var userName=document.getElementById("userName").value;
                req.open("GET","servlet/AjaxTest?name"+userName,true); //与服务端建立连接(请求方式post或get,地址,true表示异步)
                req.onreadystatechange = callback; //指定回调函数,的属性名不能加括号
                req.send(null); //发送请求
            }
        }
        
        function callback() //回调函数,对服务端的响应处理,监视response状态
        {
            if(req.readystate==4) //请求状态为4表示成功
            {
                if(req.status==200) //http状态200表示OK
                {
                    Dispaly(); //所有状态成功,执行此函数,显示数据
                }
                else //http返回状态失败
                {
                    alert("服务端返回状态" + req.statusText);
                }
            }
            else //请求状态还没有成功,页面等待
            {
                document .getElementById ("result").innerHTML ="数据加载中";
            }
        }
        
        function Dispaly() //接受服务端返回的数据,对其进行显示
        {
            document .getElementById ("result").innerHTML =req.responseText;
        }

 最后在你的主页面index.jsp编写一个简单的验证

  

<%@ page language="java" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>ajax测试实例一</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	<script language="javascript" src="js/verify.js" charset="utf-8"></script>
	
  </head>
  
  <body>
    <h1>ajax测试实例一</h1>
    <hr>
    <br/>
    <input type="text" id="userName">
    <input type="submit" value="检验" onclick="creatReq()">
    <span id="result"></span>
  </body>
</html>

 

 

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