java中javabean、list、map格式转换为json格式

在使用json的时候，麻烦的是要吧java后台的各种数据转化为json格式输出，下面列举几种情况。

首先你要引入的包有：六个常用的包 1）commons-logging-1.0.4.jar、2）commons-lang-2.3.jar、3）commons-collections-3.2.jar 、4）commons-beanutils-1.7.0.jar、5）json-lib-2.2.1-jdk15.jar、6）ezmorph-1.0.4.jar

如果用到框架还要引用struts的插件jsonplugin.jar

普通JavaBean转成json格式

1.转成JSONArray类型

User user = new User();

user.setUsername("红领巾");

user.setPassword("1234");

JSONArray json = JSONArray.fromObject(user);

System.out.println(json);//[{"password":"1234","username":"红领巾"}]

response.getWriter().print(json.toString());

2.转成JSONObject类型

JSONObject jsonObj = JSONObject.fromObject(user);

System.out.println(jsonObj);//{"password":"1234","username":"cxl"}

response.getWriter().print(jsonObj);

在js文件取数据

alert(data.username);

alert(data.password);

List转成json格式

List<User> users = new ArrayList<User>();

User user = new User();

user.setUsername("cxl");

user.setPassword("1234");

User u = new User();

u.setUsername("lhl");

u.setPassword("1234");

users.add(user);

users.add(u);

1.转成JSONArray类型

JSONArray json = JSONArray.fromObject(users);

System.out.println(json.toString());

//[{"password":"1234","username":"cxl"},

{"password":"1234","username":"lhl"}]

response.getWriter().print(json.toString());

js中取数据：alert(alert(data[0].username));

2.转成JSONObject类型

不可直接使用JSONObject jsonObj = JSONObject.fromObject(users);

可通过下列方式

JSONObject jsonObj = new JSONObject();

jsonObj.put("users", users);

jsonObj.put("u", u);

System.out.println(jsonObj);

{"users":[{"password":"1234","username":"cxl"},

{"password":"1234","username":"lhl"}],

"u":{"password":"1234","username":"lhl"}}

response.getWriter().print(jsonObj);

js中取数据：alert(data.users[0].username);

alert(data.u[0].username);

Map转成json格式

Map<String,Object> map = new HashMap<String,Object>();

map.put("users", users);

map.put("u", u);

1.转成JSONArray类型

JSONArray json = JSONArray.fromObject(map);

System.out.println(json.toString());// [{"users":

[{"password":"1234","username":"cxl"},

{"password":"1234","username":"lhl"}],"u":

{"password":"1234","username":"lhl"}}]

response.getWriter().print(json.toString);

js中取数据：alert(data[0].users[0].username);

2.转成JSONObject类型

JSONObject json = JSONObject.fromObject(map);

System.out.println(json);//

{"user":[{"password":"1234","username":"cxl"},

{"password":"1234","username":"lhl"}],"u":

{"password":"1234","username":"lhl"}}

response.getWriter().print(json);

js中取数据：alert(data.user[0].username);

不要问我是谁，请叫我红领巾