概念

javascript object notation js標(biāo)示對(duì)象的一種方式

作用

1、標(biāo)示數(shù)據(jù)，鍵值對(duì)形式 2、保存數(shù)據(jù) 3、json可以作為數(shù)據(jù)交換的格式

特點(diǎn)

輕量級(jí)，原生js

json對(duì)象 本質(zhì)就是js代碼 var aa={"name":"lisu"}
json數(shù)據(jù) 字符串
eval();

json數(shù)據(jù)

map形式

1、key/value

{"name":"zhangsan","age":"30"};

2、object

{"stu":{"name":"lisi","age":"21"}}

3、array

{"tea":[
        {"name":"lisi","age":"21"},
        {"name":"zhangsan","age":"22"}
    ]
}

4、復(fù)雜嵌套

{
    "stu2":[
        {"sex":0,"username":"lisi"},{"sex":0,"username":"zhaoliu"},
        {"password":"123","sex":0,"username":"zhangsan"}
    ],
    "stu1":{"password":"123","sex":1,"username":"zhangsan"}
}

list形式

[
    {"name":"lisi","age":"21"},
    {"name":"zhangsan","age":"22"}
]

[
    [
        {"name":"lisi","age":"21"},
        {"name":"zhangsan","age":"22"}
    ],
    [
        {"name":"lisi","age":"21"},
        {"name":"zhangsan","age":"22"}
    ]
]

json工具類(lèi)

訪問(wèn)官網(wǎng)http://www.json.org/
找到j(luò)ava平臺(tái)的json工具類(lèi)，例如json-java
到github下載源碼
導(dǎo)入到eclipse，導(dǎo)出jar

json-java的使用

javabean對(duì)象轉(zhuǎn)成json對(duì)象

User user=new User("zhaoliu", "123");
JSONObject json=new JSONObject(user);//將user對(duì)象轉(zhuǎn)成json對(duì)象

list對(duì)象轉(zhuǎn)成json對(duì)象

User user1=new User("lisi","123");
User user2=new User("zhaoliu","123");
User user3=new User("zhangsan","123");

List<User> list=new ArrayList<User>();
list.add(user1);
list.add(user2);
list.add(user3);

JSONArray json=new JSONArray(list);//將list<User>轉(zhuǎn)成json對(duì)象