第三方插件将数据转成json

public class TestBean2Json {
    private static void javabean2json() {
        City city = new City(1,"陕西");
        JSONArray jSONArray = JSONArray.fromObject(city);
        String jsonJAVA = jSONArray.toString();
        System.out.println(jsonJAVA);
        //[{"id":1,"name":"陕西"}]
    }

MAP：
private static void map2json() {
        
        List cityList = new ArrayList();
        cityList.add(new City(1,"西安"));
        cityList.add(new City(2,"临潼"));
        
        Map map = new LinkedHashMap();
        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":"西安"},{"id":2,"name":"临潼"}]}]
        
        jsonJAVA = jsonJAVA.substring(1,jsonJAVA.length()-1);
        System.out.println(jsonJAVA);
    }

List：
    private static void javabeanlist2json() {
        List cityList = new ArrayList();
        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 list2json() {
        List cityList = new ArrayList();
        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 citySet = new LinkedHashSet();
        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"}]
    }