参考链接：
https://blog.csdn.net/DQ1005/article/details/51658587
https://blog.csdn.net/huplion/article/details/78984977
https://blog.csdn.net/huyawenz/article/details/87978469

student对象

public class User {private Integer id;private String username;private String password;public User() {}public User(Integer id, String username, String password) {this.id = id;this.username = username;this.password = password;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}@Overridepublic String toString() {return "User对象toString{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +'}';}
}

Gson解析

import com.google.gson.*;
import com.google.gson.reflect.TypeToken;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class GsonTest {/*基本数据类型["aaa","bbb"]*/public void primitiveTypeJson() {Gson gson = new Gson();List<String> stringList = new ArrayList<String>();stringList.add("aaa");stringList.add("bbb");System.out.println("-----------------基本数据类型转json-----------------");String stringListToJson = gson.toJson(stringList);System.out.println(stringListToJson);//["aaa","bbb"]System.out.println("-----------------解析基本数据类型json-----------------");JsonArray jsonArray = new JsonParser().parse(stringListToJson).getAsJsonArray();for (JsonElement jsonElement : jsonArray) {if (jsonElement.isJsonPrimitive()) {System.out.println(jsonElement.getAsString());//aaa/bbb}}System.out.println("-----------------基本数据类型json转对象-----------------");System.out.println("方式一：解析成String对象再放入List");List<String> jsonToStringList = new ArrayList<String>();JsonArray jsonArray2 = new JsonParser().parse(stringListToJson).getAsJsonArray();for (JsonElement jsonElement : jsonArray2) {if (jsonElement.isJsonPrimitive()) {jsonToStringList.add(jsonElement.getAsString());}}//aaa//bbbfor (String str : jsonToStringList) {System.out.println(str);}System.out.println("方式二：直接解析为List<String>");List<String> jsonToStringList2 = gson.fromJson(stringListToJson, new TypeToken<List<String>>() {}.getType());//aaa//bbbfor (String str : jsonToStringList2) {System.out.println(str);}}/*简单对象json操作{"id": 1,"username": "username1","password": "password1"}*/public void userJson() {Gson gson = new Gson();System.out.println("-----------------简单对象转json-----------------");User user = new User(1, "username1", "password1");String userToJson = gson.toJson(user);System.out.println(userToJson);//{"id":1,"username":"username1","password":"password1"}System.out.println("-----------------解析简单对象的json-----------------");JsonObject jsonObject = new JsonParser().parse(userToJson).getAsJsonObject();System.out.println(jsonObject.get("id").getAsInt());//1System.out.println(jsonObject.get("username").getAsString());//username1System.out.println(jsonObject.get("password").getAsString());//password1System.out.println("-----------------简单对象的json转对象-----------------");User jsonToUser = gson.fromJson(userToJson, User.class);System.out.println(jsonToUser);//User对象toString{id=1, username='username1', password='password1'}}/*简单对象数组和List[{"id": 1,"username": "username1","password": "password1"},{"id": 2,"username": "username2","password": "password2"}]*/public void userListJson() {Gson gson = new Gson();User user1 = new User(1, "username1", "password1");User user2 = new User(2, "username2", "password2");List<User> userList = new ArrayList<User>();userList.add(user1);userList.add(user2);User[] userArr = new User[2];userArr[0] = user1;userArr[1] = user2;System.out.println("-----------------List<User>转json-----------------");String userListToJson = gson.toJson(userList);//[{"id":1,"username":"username1","password":"password1"},{"id":2,"username":"username2","password":"password2"}]System.out.println(userListToJson);System.out.println("-----------------user数组转json-----------------");String userArrToJson = gson.toJson(userArr);//[{"id":1,"username":"username1","password":"password1"},{"id":2,"username":"username2","password":"password2"}]System.out.println(userArrToJson);System.out.println("List<User>转json和user数组转json是一样的");System.out.println("-----------------解析List<User>的json/user数组的json-----------------");JsonArray jsonArray = new JsonParser().parse(userListToJson).getAsJsonArray();for (JsonElement jsonElement : jsonArray) {if (jsonElement.isJsonObject()) {JsonObject jsonObject = jsonElement.getAsJsonObject();System.out.println(jsonObject.get("id").getAsInt());//1/2System.out.println(jsonObject.get("username").getAsString());//username1/username12System.out.println(jsonObject.get("password").getAsString());//password1/password2}}System.out.println("-----------------List<User>的json/user数组的json转对象-----------------");System.out.println("方式一：");List<User> jsonToUserList = new ArrayList<User>();JsonArray jsonArray2 = new JsonParser().parse(userListToJson).getAsJsonArray();for (JsonElement jsonElement : jsonArray) {//jsonElement转对象方式一User jsonToUser = gson.fromJson(jsonElement, new TypeToken<User>() {}.getType());//jsonElement转对象方式二
//            User jsonToUser = gson.fromJson(jsonElement, User.class);jsonToUserList.add(jsonToUser);}//User对象toString{id=1, username='username1', password='password1'}//User对象toString{id=2, username='username2', password='password2'}for (User user : jsonToUserList) {System.out.println(user);}System.out.println("方式二：");List<User> jsonToUserList2 = gson.fromJson(userListToJson, new TypeToken<List<User>>() {}.getType());//User对象toString{id=1, username='username1', password='password1'}//User对象toString{id=2, username='username2', password='password2'}for (User user : jsonToUserList2) {System.out.println(user);}}/* 复杂对象{"Integer": 1,"userList": [{"id": 1,"username": "username1","password": "password1"},{"id": 2,"username": "username2","password": "password2"}],"String": "String","Double": 1.23,"user": {"id": 1,"username": "username1","password": "password1"}}*/public void complexGsonTest() {Gson gson = new Gson();User user1 = new User(1, "username1", "password1");User user2 = new User(2, "username2", "password2");List<User> userList = new ArrayList<User>();userList.add(user1);userList.add(user2);Map<String, Object> map = new HashMap<String, Object>();map.put("String", "String");//字符串map.put("Integer", 1);//整数map.put("Double", 1.23);//浮点数map.put("user", user1);//对象map.put("userList", userList);//对象ListString complexJson = gson.toJson(map);//{"Integer":1,"userList":[{"id":1,"username":"username1","password":"password1"},{"id":2,"username":"username2","password":"password2"}],"String":"String","Double":1.23,"user":{"id":1,"username":"username1","password":"password1"}}System.out.println(complexJson);System.out.println("-----------------解析复杂对象的json-----------------");JsonObject jsonObject = new JsonParser().parse(complexJson).getAsJsonObject();// 字符串System.out.println(jsonObject.get("String").getAsString());// 整数System.out.println(jsonObject.get("Integer").getAsInt());// 浮点数System.out.println(jsonObject.get("Double").getAsDouble());// User:查看userJson函数具体解析JsonObject userJsonObject = jsonObject.getAsJsonObject("user");System.out.println(userJsonObject.get("id").getAsInt());System.out.println(userJsonObject.get("username").getAsString());System.out.println(userJsonObject.get("password").getAsString());// List<User>:查看userListJson函数具体解析// 获得JsonArrayJsonArray userListJsonArray = jsonObject.getAsJsonArray("userList");// 遍历JsonArrayfor (JsonElement jsonElement : userListJsonArray) {JsonObject asJsonObject = jsonElement.getAsJsonObject();System.out.println(asJsonObject.get("id").getAsInt());System.out.println(asJsonObject.get("username").getAsString());System.out.println(asJsonObject.get("password").getAsString());}System.out.println("-----------------解析复杂对象的json转成对象,基本数据类型同上-----------------");System.out.println("User对象:查看userJson函数具体解析");JsonObject userJsonObject2 = jsonObject.getAsJsonObject("user");User jsonToUser = gson.fromJson(userJsonObject2, new TypeToken<User>() {}.getType());System.out.println(jsonToUser);System.out.println("List<User>:查看userListJson函数具体解析");JsonArray userListJsonArray2 = jsonObject.getAsJsonArray("userList");List<User> users = gson.fromJson(userListJsonArray2, new TypeToken<List<User>>() {}.getType());for (User user : users) {System.out.println(user);}}public static void main(String[] args) {GsonTest gsonTest = new GsonTest();gsonTest.complexGsonTest();}}