Ajax的三种实现及JSON解析

package ajax.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;  
  
/** 
 * Ajax例子后台处理程序 
 * @author bing 
 * @version 2011-07-07 
 * 
 */  
public class TestAjaxServlet extends HttpServlet {  
    public void doGet(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
  
        response.setContentType("text/html;charset=utf-8");  
        PrintWriter out = response.getWriter();  
          
        String name = request.getParameter("name");  
        String age = request.getParameter("age");  
          
        System.out.println("{"name":"" + name + "","age":"" + age + ""}");  
        out.print("{"name":"" + name + "","age":" + age + "}");  
          
        out.flush();  
        out.close();  
    }  
    public void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
  
        doGet(request,response);  
    }  
  
}  
 

<div id="show">显示区域</div>  
<div id="parameters">  
    name:<input id="name" name="name" type="text" /><br />  
    age:<input id="age" name="age" type="text" /><br />  
</div>  

<script type="text/javascript" src="prototype.js"></script>  
    <script type="text/javascript">  
        function prototypeAjax()  
        {         
        var url = "servlet/testAjax";//请求URL  
        var params = Form.serialize("parameters");//提交的表单  
      var myAjax = new Ajax.Request(  
  
        url,{  
            method:"post",// 请求方式   
            parameters:params, // 参数  
            onComplete:pressResponse, // 响应函数  
            asynchronous:true  
        });  
        $("show").innerHTML = "正在处理中...";  
        }  
        function pressResponse(request)  
        {  
        var obj = request.responseText; // 以文本方式接收  
        $("show").innerHTML = obj;  
        var objJson = request.responseText.evalJSON(); // 将接收的文本用解析成Json格式  
        $("show").innerHTML += "name=" + objJson['name'] + " age=" + objJson['age'];  
  
        }  
</script>  
<input id="submit" type="button" value="提交" onclick="prototypeAjax()" /><br />  

<script type="text/javascript" src="jquery-1.3.2.min.js"></script>  
<script type="text/javascript" src="json2.js"></script>  
<input id="submit" type="button" value="提交" /><br />  
<script type="text/javascript">  
        function jqueryAjax()     
        {     
            var user={"name":"","age":""};     
            user.name= $("#name").val();     
            user.age=$("#age").val();   
            var time = new Date();            
            $.ajax({     
                 url: "servlet/testAjax?time="+time,     
                 data: "name="+user.name+"&age="+user.age,     
                 datatype: "json",//请求页面返回的数据类型     
                 type: "GET",     
                 contentType: "application/json",//注意请求页面的contentType 要于此处保持一致     
                 success:function(data) {//这里的data是由请求页面返回的数据    
                 var dataJson = JSON.parse(data); // 使用json2.js中的parse方法将data转换成json格式   
                 $("#show").html("data=" + data + " name="+dataJson.name+"  age=" + dataJson.age);     
                 },     
                 error: function(XMLHttpRequest, textStatus, errorThrown) {     
                   $("#show").html("error");  
                 }     
           });     
        }  
       $("#submit").bind("click",jqueryAjax); // 绑定提交按钮  
 </script>  

<script type="text/javascript">  
        var xmlhttp;   
        function XMLHttpRequestAjax()   
        {  
            // 获取数据  
         var name = document.getElementById("name").value;   
             var age = document.getElementById("age").value;   
         // 获取XMLHttpRequest对象  
         if(window.XMLHttpRequest){  
            xmlhttp = new XMLHttpRequest();    
         }else if(window.ActiveXObject){   
            var activxName = ["MSXML2.XMLHTTP","Microsoft.XMLHTTP"];     
            for(var i = 0 ; i < activexName.length; i++){  
               try{  
                   xmlhttp = new ActiveXObject(activexName[i]);    
                   break;   
               }catch(e){}  
            }  
         }  
             xmlhttp.onreadystatechange = callback;  //回调函数  
             var time = new Date();// 在url后加上时间，使得每次请求不一样  
             var url = "servlet/testAjax?name="+name+"&age="+age+"&time="+time;  
             xmlhttp.open("GET",url,true); // 以get方式发送请求  
             xmlhttp.send(null);   // 参数已在url中，所以此处不需要参送  
        }       
        function callback(){     
           if(xmlhttp.readyState == 4){     
              if(xmlhttp.status == 200){ // 响应成功    
                  var responseText = xmlhttp.responseText;   // 以文本方式接收响应信息  
                  var userdiv = document.getElementById("show");  
                  var responseTextJson = JSON.parse(responseText); // 使用json2.js中的parse方法将data转换成json格式   
                  userdiv.innerHTML=responseText + " name=" + responseTextJson.name + " age=" + responseTextJson.age;  
              }  
           }          
        }  
</script>  
<input id="submit" type="button" value="提交" onclick="XMLHttpRequestAjax()" /><br />