1，jsp

<title>测试Ajax</title><script type="text/javascript" src="jquery-1.10.1.js"></script><script type="text/javascript"> $(function(){ $("#xxx").blur(function(){ var value = $('#xxx').val(); $.ajax({ url:"/java_web02/AjaxServlet", //要请求服务器的url data:{val:value}, //这是一个对象，表示请求参数val=xx, 服务器端可以使用request.getParameter()来获取 async:true, //是否为异步请求 cache:false, //是否缓存结果 type:"POST", //请求方式 dataType:"json", //服务器返回的数据是什么类型 success:function(result){//这个函数在服务器执行成功时会被调用，参数result就是服务器返回的值 $('label').text(result.name + "," + result.age); } }); }); });</script></head><body> 用户名：<input type="text" name="name" id="xxx"/><label></label><br /> 年龄：<input type="text" name="age" /></body>

2，servlet

@WebServlet("/AjaxServlet")public class AjaxServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置编码格式 request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); //获取前台传来的数据 String value = request.getParameter("val"); if(value.equals("xiaoxiao")){ String str = "{\"name\":\"好人\", \"age\":23}"; //用\来转义 response.getWriter().print(str); }else { String str = "{\"name\":\"坏人\", \"age\":89}"; response.getWriter().print(str); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}