ajax 三种实现方法实例代码

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 />