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);
     }
 }