jquery与ajax

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这是一个简单的 GET请求功能以取代复杂 $.ajax。请求成功时可调用回调函数。如果需要在出错时执行函数，请使用 $.ajax。示例代码：

$.ajax({

type : "GET",

contentType: "application/x-www-form-urlencoded; charset=utf-8",

url : "ServiceServlet",

data : "username="+username+"&password="+password,

dataType : "xml",

success : callback,

error:callbackErr

});

下面是jQuery官方给出的完整的Ajax事件列表：

· ajaxStart (Global Event)
This event is broadcast if an Ajax request is started and no other Ajax requests are currently running.

· beforeSend (Local Event)
This event, which is triggered before an Ajax request is started, allows you to modify the XMLHttpRequest object (setting additional headers, if need be.)

· ajaxSend (Global Event)
This global event is also triggered before the request is run.

· success (Local Event)
This event is only called if the request was successful (no errors from the server, no errors with the data).

· ajaxSuccess (Global Event)
This event is also only called if the request was successful.

· error (Local Event)
This event is only called if an error occurred with the request (you can never have both an error and a success callback with a request).

· ajaxError (Global Event)
This global event behaves the same as the local error event.

· complete (Local Event)
This event is called regardless of if the request was successful, or not. You will always receive a complete callback, even for synchronous requests.

· ajaxComplete (Global Event)
This event behaves the same as the complete event and will be triggered every time an Ajax request finishes.

· ajaxStop (Global Event)
This global event is triggered if there are no more Ajax requests being processed.

具体的全局事件请参考API文档。

完整代码示例：前段

<%@ page language="java" import="java.util.*" 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>My JSP 'index.jsp' starting page</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 type="text/javascript"  src="jquery-1.8.3.js"></script><script>    function doConfig(){    //  var username = document.getElementById("username").value; //  var password = document.getElementById("password").value;   var username = $("#username").val();   var password = $("#password").val();   $.ajax({        type : "GET",        contentType: "application/x-www-form-urlencoded; charset=utf-8",        url : "ServiceServlet",        data : "username="+username+"&password="+password,        dataType : "xml",        success : callback,        error:callbackErr    });       }   function callback(data){      var  name ="";     $(data).find('service').each(function(i){        name=$(this).find('info').text();      });   alert(name);   }  function callbackErr(data){      alert("error");   }</script>  </head>    <body>    <table>         <tr>            <td>用户名：</td>            <td><input id="username" /></td>         </tr>         <tr>            <td>密码：</td>            <td><input id="password" /></td>         </tr>         <tr>            <td></td>            <td><input type="submit" onclick="doConfig()" /></td>         </tr>    </table>  </body></html>

后台代码：

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 ServiceServlet 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 {   String username = request.getParameter("username");   String password = request.getParameter("password");      System.out.println("用户名："+username+"密码："+password);   response.setContentType("text/xml");   response.setCharacterEncoding("utf-8");   response.getWriter().write("<?xml version=\"1.0\" encoding=\"utf-8\"?><service><info>success</info></service>");   } public void init() throws ServletException {}}