1.什么是json

json是一种与开发语言无关的数据传输格式，全程是JavaScript Object Notation;具有易读编写和程序的解析和生产。

2.简单的Json示例

{
"name" : "张三"，
"id":"1"
}

3.标准Json数据表示
数据结构：

• Object：
  使用花括号{}包含的键值对结构，Key必须是String类型，value可以为任何基本类型或者数据结构
• Array
  使用中括号来起始，用逗号来隔开

 var employees = [
    { "firstName":"Bill" , "lastName":"Gates" },
    { "firstName":"George" , "lastName":"Bush" },
    { "firstName":"Thomas" , "lastName": "Carter" }
    ];

数据演示

{
"name" : "王小二",
"age":"25.2",
"school":"蓝翔",
"major":["挖掘机","炒菜"]
"has_girlfriend" :false
}

3.解析Json

JavaScript原生支持json,可以用eval()函数来解析json，把json文本数据转换成JavaScript对象

var text = "{"name" : "123", age : 1}"
var aa = eval("(" + txt + ")");
alert(aa);

使用JsonObject

导入相关jar包

导入开发包

• commons-io-2.0.1.jar
• commons-lang-2.5.jar
• commons-collections-3.1.jar
• commons-beanutils-1.7.0.jar
• ezmorph-1.0.3.jar
• json-lib-2.1-jdk15.jar
  案例：

public class TestBean2Json {
    private static void javabean2json() {
        City city = new City(1,"广州");
        JSONArray jSONArray = JSONArray.fromObject(city);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"广州"}]
    }
    private static void list2json() {
        List<City> cityList = new ArrayList<City>();
        cityList.add(new City(1,"广州"));
        cityList.add(new City(2,"珠海"));
        JSONArray jSONArray = JSONArray.fromObject(cityList);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]
    }
    private static void set2json() {
        Set<City> citySet = new LinkedHashSet<City>();
        citySet.add(new City(1,"广州"));
        citySet.add(new City(2,"珠海"));
        JSONArray jSONArray = JSONArray.fromObject(citySet);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]
    }
    private static void javabeanlist2json() {
        List<City> cityList = new ArrayList<City>();
        cityList.add(new City(1,"中山"));
        cityList.add(new City(2,"佛山"));
        Province province = new Province(1,"广东",cityList);
        
        JSONArray jSONArray = JSONArray.fromObject(province);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        /*
          [
             {
              "id":1,
              "name":"广东"
              "cityList":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}],
             }
          ]
          */
    }
    private static void map2json() {
        
        List<City> cityList = new ArrayList<City>();
        cityList.add(new City(1,"中山"));
        cityList.add(new City(2,"佛山"));
        
        Map<String,Object> map = new LinkedHashMap<String,Object>();
        map.put("total",cityList.size());//表示集合的长度
        map.put("rows",cityList);//rows表示集合
        
        JSONArray jSONArray = JSONArray.fromObject(map);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"total":2,"rows":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}]}]
        
        jsonJAVA = jsonJAVA.substring(1,jsonJAVA.length()-1);
        System.out.println(jsonJAVA);
    }