function verify(){  

    //1.獲取文本框中的內(nèi)容  

    //jquery查找節(jié)點(diǎn)的方式，參數(shù)加#加上id屬性可以找到一個節(jié)點(diǎn)  

    //jquery的方法返回的都是jquery的對象，可以繼續(xù)在上面執(zhí)行其他的jquery方法  

    var jqueryObj = $("#userName");  

    //獲取節(jié)點(diǎn)的值  

    var userName = jqueryObj.val();  

    //alert(userName);  

    //2.將文本框中的數(shù)據(jù)發(fā)送給服務(wù)遄的servlet  

    //使用jquery的XMLHTTPrequest對象get請求的封裝  

    //$.get("servlet/AjaxServlet?name="+userName,null,callback);  

    //使用jquery的xmlhttprequest對象get請求的封裝  

    //var obj = {name:"123",age:20};  

    $.ajax({  

        type: "POST",  

        url: "servlet/AjaxXmlServlet",  

        data: "name=" + userName,//發(fā)送給服務(wù)端的數(shù)據(jù)  

        dataType: "xml",//告訴jquety返回的數(shù)據(jù)格式  

        success: callback//定義交互完成，并且服務(wù)端在下返回數(shù)據(jù)的回調(diào)函數(shù) 

    });  

}  

// 回調(diào)函數(shù)  

function callback(data){  

    //3.接收服務(wù)器端返回的數(shù)據(jù)  

    //alert("服務(wù)器端的數(shù)據(jù)回來了！")  

    //需要將data這個對象中的數(shù)據(jù)解析出來  

    //首先需要將dom的對象轉(zhuǎn)換成jquery的對象  

    var jqueryObj = $(data);  

    //獲取message節(jié)點(diǎn)  

    var message = jqueryObj.children();  

    //獲取文本內(nèi)容  

    var text = message.text();  

    //4.將服務(wù)器返回的數(shù)據(jù)動態(tài)的顯示在網(wǎng)頁上  

    //找到保存結(jié)果信息的節(jié)點(diǎn)  

    var resultObj = $("#result");  

    //動態(tài)的改變頁面中DIV節(jié)點(diǎn)的內(nèi)容  

    resultObj.html(text);  

    //alert("");  

}

2. AjaxXmlServlet.java如下：

復(fù)制代碼代碼如下:

package com.panlong.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 AjaxXmlServlet extends HttpServlet {  

    private static final long serialVersionUID = 1L;  

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)  

            throws ServletException, IOException {  

            Integer total = (Integer) req.getSession().getAttribute("total");  

            int temp = 0;  

            if(total == null ){  

                temp = 1;  

            }else{  

                temp = total.intValue() + 1;  

            }  

        req.getSession().setAttribute("total",total.intValue()+temp);  

        try {  

            //1.取參數(shù)  

            resp.setContentType("text/xml;charset=GB2312");  

            PrintWriter out = resp.getWriter();  

            StringBuilder builder = new StringBuilder();  

            String old = req.getParameter("name");  

            //2、檢查參數(shù)是否有問題  

            String name = old;  

            builder.append("<message>");  

            if("".equals(old) || old == null){  

                builder.append("用戶名必須輸入").append("</message>");  

            }  

            else      

                 {  

            if("lila".equals(name)){  

                builder.append("該用戶名已經(jīng)注冊").append("</message>");

            }else{  

                    builder.append("該用戶名未注冊，您可以注冊["+name+"]這個用戶名").append("</message>");  

            }  

         }  

            out.println(builder.toString());  

        }catch (Exception e) {  

            e.printStackTrace();  

        //3.檢驗(yàn)操作  

        }  

    }  

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)  

            throws ServletException, IOException {  

        doGet(req, resp);  

    }  

}

3. 前臺html頁面

復(fù)制代碼代碼如下:

<!DOCTYPE html>  

<html>  

  <head>  

    <title>AJAX實(shí)例</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=GB2312">

    <script type="text/javascript" src="js/AjaxJqueryXml.js"></script>  

    <script type="text/javascript" src="js/jquery.js"></script>  

    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->  

  </head>  

  <body>  

        <font color="blue" size="2">請輸入用戶名：</font>   

         <input type="text" id="userName" /><font color="red" size="2"><span id="result" >*</span></font><br/><br/>  

         <input type="submit" name="提交" value="提交"  onclick="verify()"/>  

  </body>  

</html>