json与list，map，String之间的互转

package tools;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import net.sf.json.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.google.gson.Gson;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import bean.Student;

public class Json {
    public static void main(String[] args) {
        //json对象转json字符串
        jsonObjToJsonStr();
        //json字符串转json对象
        jsonStrToJsonObj();
        //list转json
        listToJson();
        //json转list
        jsonToList();
        //json转map
        jsonToMap();
        //map转json
        mapToJson();
    }

    /**
     * map转json
     */
    private static void mapToJson() {
        ObjectMapper mapper = new ObjectMapper();
        String json = "";
        Map<String, String> map = new HashMap<String,String>();
        map.put("name", "JSON");
        map.put("age", "23");
        map.put("address", "北京市西城区");
        try {
            json = mapper.writeValueAsString(map);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        System.out.println(json);
    }

    /**
     * json转map
     */
    private static void jsonToMap() {
        String json = "{\"name\":\"JSON\",\"address\":\"北京市西城区\",\"age\":23}";
        Map<String, String> map = new HashMap<String, String>();
        ObjectMapper mapper = new ObjectMapper();
        try{  
            map = mapper.readValue(json, new TypeReference<HashMap<String,String>>(){});  
            System.out.println(map);  
        }catch(Exception e){  
            e.printStackTrace();  
        }
    }

    /**
     * json转list
     */
    private static void jsonToList() {
       //json转成list
        String json ="[\"abc\",\"123\"]";
        JSONArray jsonArray = JSONArray.fromObject(json);
        List<String> list = (List) JSONArray.toCollection(jsonArray);
        for (int i = 0; i < list.size(); i++) {
           System.out.println(list.get(i));  
       }
    }

    /**
     * list转json
     */
    private static void listToJson() {
        List<String> list = new ArrayList<String>();
        list.add("abc");
        list.add("123");
        //list转成json
        String json =JSONArray.fromObject(list).toString();
        System.out.println(json);
        //运行：["abc","123"]
    }

    /**
     * json字符串转json对象
     */
    private static void jsonStrToJsonObj() {
        //json转为json对象，取属性值
        String json ="{\"name\":\"JSON\",\"address\":\"北京市西城区\",\"age\":23}";
        JSONObject jo = (JSONObject) JSONObject.parse(json);
        String add = jo.getString("address");
        System.out.println(add);
    }

    /**
     * json对象转json字符串
     */
    private static void jsonObjToJsonStr() {
        Student stu=new Student();
        stu.setName("JSON");
        stu.setAge(23);
        stu.setAddress("北京市西城区");
        //对象转换为json字符串
        Gson gson = new Gson();
        String json = gson.toJson(stu);
        System.out.println(json);
    }
}