package com.wch.util;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import com.google.gson.Gson;

import com.google.gson.reflect.TypeToken;

import com.wch.entity.Users;

public class JsonUtil {

public static void main(String[] args) {

String str = "[{\"id\":1,\"username\":\"whwu123\",\"password\":\"mcgrady1\",\"nickname\":\"伍春晖\"}]";

Users users = new Users(1, "whwu123", "mcgrady1", "伍春晖");

Users users2 = new Users(2, "whwu1234", "mcgrady12", "伍春晖2");

List<Users> list = new ArrayList<Users>();

list.add(users);

list.add(users2);

Map<String, List<Users>> map = new HashMap<String, List<Users>>();

map.put("wch", list);

System.out.println(mapToJson(map));

}

/**

* 把对象转换成json字符串

* @param obj 传入需要转换的object对象

* @return

*/

public static String ParseJson(Object obj) {

Gson gson = new Gson();

String str = gson.toJson(obj);

return str;

}

/**

* 把字符串转成成对象

* @param <T>

* @param jsonStr

* @return

*/

public static void jsonToJavaBean(String json) {

Gson gson = new Gson();

Users person = gson.fromJson(json, Users.class);//对于javabean直接给出class实例

}

/**

* map to json

*

* @param map

* @return

*/

public static String mapToJson(Map<String, List<Users>> map) {

Gson gson = new Gson();

String json = gson.toJson(map);

return json;

}

/**

* json字符串转List集合

*/

public static void jsonToList(String json) {

Gson gson = new Gson();

List<Users> list = gson.fromJson(json, new TypeToken<List<Users>>() {}.getType());//对于不是类的情况，用这个参数给出

for (Users users : list) {

System.out.println(users.getNickname());

}

}

public static void jsonToMap(String json) {

Gson gson = new Gson();

Map<String, Users> maps = gson.fromJson(json, new TypeToken<Map<String, Users>>() {

}.getType());

for (Map.Entry<String, Users> entry : maps.entrySet()) {

System.out.println("key: " + entry.getKey() + " " + "value: " + entry.getValue());

}

}

}