这里有两个例子，一个是关于登录验证的，一个是异步加载数据的
1、regist.jsp
<%@ 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 ‘regist.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="js/jquery-1.11.0.min.js"></script> ???<script type="text/javascript"> ???????$(function(){ ???????????$("#username").blur(function(){ ???????????????$.ajax({ ???????????????????url:"checkUsername", ???????????????????data:{"name":$("#username").val()}, ???????????????????success:function(data){ ???????????????????????//alert(data); ???????????????????????var src = eval("("+data+")"); ???????????????????????$("#sty").html(src.msg); ???????????????????} ???????????????}); ???????????}); ???????????????????????????????????$(":button").click(function(){ ???????????????$.ajax({ ???????????????????url:"findAll", ???????????????????success:function(data){ ???????????????????????$("tr").remove("tr:not(:eq(0))"); ???????????????????????//alert(data); ???????????????????????var src = eval("("+data+")"); ???????????????????????var table = $("table"); ???????????????????????for(var i=0;i<src.length;i++){ ???????????????????????????//alert(src[i].name); ???????????????????????????var tr = $("<tr></tr>"); ???????????????????????????var cell1 = $("<td>"+src[i].name+"</td>"); ???????????????????????????var cell2 = $("<td>"+src[i].sex+"</td>"); ???????????????????????????var cell3 = $("<td>"+src[i].age+"</td>"); ???????????????????????????cell1.appendTo(tr); ???????????????????????????cell2.appendTo(tr); ???????????????????????????cell3.appendTo(tr); ???????????????????????????tr.appendTo(table); ???????????????????????} ???????????????????} ???????????????}); ???????????}); ???????????????????}); ???</script> ?</head> ???<body> ???<form action="registAction"> ???????用户名:<input type="text" name="username" id="username"/><span id="sty"></span><br/> ???????密码:<input type="password" name="pwd" id="pwd"/><br/> ???????<input type="submit" value="注册"/> ???</form> ???<input type="button" value="查看全部"/><br/> ???<table> ???????<tr> ???????????<td>姓名</td> ???????????<td>性别</td> ???????????<td>年龄</td> ???????</tr> ???</table> ?</body></html>2、导入JSON的必须包
3、CheckUsername.java
package com.cn.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;import net.sf.json.JSONObject;public class CheckUsername extends HttpServlet { ???public void doGet(HttpServletRequest request, HttpServletResponse response) ???????????throws ServletException, IOException { ???????this.doPost(request, response); ???????????} ???public void doPost(HttpServletRequest request, HttpServletResponse response) ???????????throws ServletException, IOException { ???????response.setContentType("text/html;charset=utf-8"); ???????PrintWriter out = response.getWriter(); ???????????????String username = request.getParameter("name"); ???????????????/* ????????* json格式 ????????* {"name":"jack","age":"18"} ????????*/ ???????//String msg = ""; ???????//创建json对象 ???????JSONObject job = new JSONObject(); ???????????????if(username.equals("jack")){ ???????????//msg = "{\"msg\":\"当前用户已存在不可注册\"}"; ???????????job.put("msg", "当前用户已存在不可注册"); ???????}else{ ???????????//msg = "{\"msg\":\"当前用户可注册\"}"; ???????????job.put("msg", "当前用户可注册"); ???????} ???????????????//out.print(msg); ???????out.print(job); ???????out.flush(); ???????out.close(); ???}}4、User.java
package com.cn.pojo;public class User { ???private String name; ???private String sex; ???private int age; ???public String getName() { ???????return name; ???} ???public void setName(String name) { ???????this.name = name; ???} ???public String getSex() { ???????return sex; ???} ???public void setSex(String sex) { ???????this.sex = sex; ???} ???public int getAge() { ???????return age; ???} ???public void setAge(int age) { ???????this.age = age; ???} ???public User() { ???????super(); ???????// TODO Auto-generated constructor stub ???} ???public User(String name, String sex, int age) { ???????super(); ???????this.name = name; ???????this.sex = sex; ???????this.age = age; ???}}5、FindAll.java
package com.cn.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;import net.sf.json.JSONArray;import net.sf.json.JSONObject;public class FindAll extends HttpServlet { ???public void doGet(HttpServletRequest request, HttpServletResponse response) ???????????throws ServletException, IOException { ???????this.doPost(request, response); ???} ???public void doPost(HttpServletRequest request, HttpServletResponse response) ???????????throws ServletException, IOException { ???????response.setContentType("text/html;charset=utf-8"); ???????PrintWriter out = response.getWriter(); ???????????????//json数组 ???????//[{"name":"jack","sex":"男","age":"18"},{"name":"lily","sex":"女","age":"17"},{"name":"tom","sex":"男","age":"18"}] ???????????????//json对象 ???????JSONObject obj1 = new JSONObject(); ???????obj1.put("name", "jack"); ???????obj1.put("sex", "男"); ???????obj1.put("age", "18"); ???????????????JSONObject obj2 = new JSONObject(); ???????obj2.put("name", "lily"); ???????obj2.put("sex", "女"); ???????obj2.put("age", "17"); ???????????????JSONObject obj3 = new JSONObject(); ???????obj3.put("name", "tom"); ???????obj3.put("sex", "男"); ???????obj3.put("age", "18"); ???????????????//创建json数组 ???????JSONArray ja = new JSONArray(); ???????ja.add(obj1); ???????ja.add(obj2); ???????ja.add(obj3); ???????????????out.print(ja); ???????out.flush(); ???????out.close(); ???}}用jQuery和Json实现Ajax异步请求
原文地址：http://www.cnblogs.com/Vito-Yan/p/7533875.html