1.首先下载json所以依赖的包， Json-lib 最新版 json-lib-2.3-jdk15.jar，其官方网站是：http://json-lib.sourceforge.net/可以直接download，细心的你会发现其网站页面里面有提示它还需要其他包：
Json-lib requires (at least) the following dependencies in your classpath:
•jakarta commons-lang 2.4
•jakarta commons-beanutils 1.7.0
•jakarta commons-collections 3.2
•jakarta commons-logging 1.1.1
•ezmorph 1.0.6
下载地址分别是：
http://commons.apache.org/lang/
http://commons.apache.org/beanutils/
http://commons.apache.org/collections/
http://commons.apache.org/logging/
http://ezmorph.sourceforge.net/
2.首先先见一个小web项目
User类：
package com.json; public class User { String username; String password; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
servlet :
package com.json; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import net.sf.json.JSONArray; public class TestJson 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 { response.setContentType("text/html"); String str= =request.getParameter("name");//得到ajax传递过来的paramater PrintWriter out = response.getWriter(); List list = new ArrayList();//传递List Map m=new HashMap();//传递Map User u1=new User(); u1.setUsername("zah"); u1.setPassword("123"); User u2=new User(); u2.setUsername("ztf"); u2.setPassword("456"); list.add(u1); //添加User对象 list.add(u2); //添加User对象 m.put("u1", u1); m.put("u2", u2); JSONArray jsonArray2 = JSONArray.fromObject( list ); //把java数组转化成转化成json对象 JSONObject jo=JSONObject.fromObject(m); //转化Map对象 out.print(jsonArray2);//返给ajax请求 out.print(jo);//返给ajax请求 } }
ajax实现:
<script type="text/javascript" src="js/jquery.js"></script> <script type="text/javascript"> function test(){ $.ajax({ type:"POST", //请求方式 url:"testjson", //请求路径 cache: false, data:"name=zah", //传参 dataType: 'json', //返回值类型 success:function(json){ alert(json[0].username+" " json[0].password); //弹出返回过来的List对象 } }); } </script>
<body> <input type="button" name="b" value="测试" onclick=test()> </body>
输出：zah 123
访问Map的话直接把返回函数改成如下即可：
success:function(json){
alert(json.u1.username)
}