String转换为JSON的几种方式
common
采用springboot创建案例
1.导入依赖
2.添加通用实体类
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
private int id;
private String username;
private String password;
}
@Data
@NoArgsConstructor
@AllArgsConstructor
public class UserGroup {
private String name;
private List
}
一、fastjson
@Test
public void test1(){
//简单对象转换
User user = new User(1,"root", "123456");
System.out.println("初始化类：" + user);
//调用toJSONString()
String userJson = JSON.toJSONString(user);
System.out.println("java类转换为json串：" + userJson);//{"id":1,"password":"123456","username":"root"}
JSONObject jsonObject = JSONObject.parseObject(userJson);
Integer id = jsonObject.getInteger("id");
String username = jsonObject.getString("username");
String password = jsonObject.getString("password");
System.out.println(id +" : "+username + " : " + password);
}
@Test
public void test2(){
//集合转json串
User user1 = new User(1,"zhangsan", "111111");
User user2 = new User(2,"lisi", "222222");
List
users.add(user1);
users.add(user2);
System.out.println("初始化类：" + users);
//调用toJSONString()
String userJson = JSON.toJSONString(users);
System.out.println("集合转json串：" + userJson);
JSONArray jsonArray = JSONArray.parseArray(userJson);
for (int i = 0; i < jsonArray.size(); i++) {
Object obj = jsonArray.get(i);
System.out.println(obj);// {"password":"111111","id":1,"username":"zhangsan"}
String userJson1 = JSON.toJSONString(obj);
JSONObject jsonObject = JSONObject.parseObject(userJson1);
Integer id = jsonObject.getInteger("id");
String username = jsonObject.getString("username");
String password = jsonObject.getString("password");
System.out.println(id +" : "+username + " : " + password);
}
}
@Test
public void test3(){
//集合转json串
User user1 = new User(1,"zhangsan", "111111");
User user2 = new User(2,"lisi", "222222");
List
users.add(user1);
users.add(user2);
System.out.println("初始化类：" + users);
//复杂java类转换对象
UserGroup userGroup = new UserGroup("userGroup", users);
System.out.println("初始化类：" + userGroup);
//调用toJSONString()
String userGroupJson = JSON.toJSONString(userGroup);
System.out.println("复杂java类转换json串：" + userGroupJson);
JSONObject jsonObjects = JSONObject.parseObject(userGroupJson);
String name = jsonObjects.getString("name");
String usersArray = jsonObjects.getString("users");
System.out.println(name);
System.out.println(usersArray);
JSONArray jsonArray = JSONArray.parseArray(usersArray);
for (int i = 0; i < jsonArray.size(); i++) {
Object obj = jsonArray.get(i);
System.out.println(obj);// {"password":"111111","id":1,"username":"zhangsan"}
String userJson1 = JSON.toJSONString(obj);
JSONObject jsonObject = JSONObject.parseObject(userJson1);
Integer id = jsonObject.getInteger("id");
String username = jsonObject.getString("username");
String password = jsonObject.getString("password");
System.out.println(id +" : "+username + " : " + password);
}
}
PS：代码繁琐一点，但结果获取到了！！！
二、gson
@Test
public void test1(){
//简单对象转换
User user = new User(1,"root", "123456");
System.out.println("初始化类：" + user);
//创建gson对象
Gson gson = new Gson();
// 调用Gson的String toJson(Object)方法将Bean转换为json字符串
String jsonStr = gson.toJson(user);
System.out.println("java类转换为json串：" + jsonStr);
User fromJson = gson.fromJson(jsonStr, User.class);
int id = fromJson.getId();
String username = fromJson.getUsername();
String password = fromJson.getPassword();
System.out.println(id +" : "+username + " : " + password);
}
@Test
public void test2(){
//集合转json串
User user1 = new User(1,"zhangsan", "111111");
User user2 = new User(2,"lisi", "222222");
List
users.add(user1);
users.add(user2);
System.out.println("初始化类：" + users);
//创建gson对象
Gson gson = new Gson();
// 调用Gson的String toJson(Object)方法将Bean转换为json字符串
String jsonStr = gson.toJson(users);
System.out.println("java类转换为json串：" + jsonStr);
List list = gson.fromJson(jsonStr, List.class);
System.out.println(list);
for (int i = 0; i < list.size(); i++) {
Object obj = list.get(i);
String json = gson.toJson(obj);
User user = gson.fromJson(json, User.class);
int id = user.getId();
String username = user.getUsername();
String password = user.getPassword();
System.out.println(id +" : "+username + " : " + password);
}
}
@Test
public void test3(){
//集合转json串
User user1 = new User(1,"zhangsan", "111111");
User user2 = new User(2,"lisi", "222222");
List
users.add(user1);
users.add(user2);
System.out.println("初始化类：" + users);
//复杂java类转换对象
UserGroup userGroup = new UserGroup("userGroup", users);
System.out.println("初始化类：" + userGroup);
//创建gson对象
Gson gson = new Gson();
// 调用Gson的String toJson(Object)方法将Bean转换为json字符串
String userGroupJson = gson.toJson(userGroup);
System.out.println("复杂java类转换json串：" + userGroupJson);
UserGroup userGroupStr = gson.fromJson(userGroupJson, UserGroup.class);
String userGroupStrName = userGroupStr.getName();
List
System.out.println(userGroupStrName);
System.out.println(usersList);
for (int i = 0; i < usersList.size(); i++) {
Object obj = usersList.get(i);
String json = gson.toJson(obj);
User user = gson.fromJson(json, User.class);
int id = user.getId();
String username = user.getUsername();
String password = user.getPassword();
System.out.println(id +" : "+username + " : " + password);
}
}
三、Jackson
@Test
public void test1() throws JsonProcessingException {
//简单对象转换
User user = new User(1,"root", "123456");
System.out.println("初始化类：" + user);
//创建jackson对象
ObjectMapper objectMapper = new ObjectMapper();
String jsonStr = objectMapper.writeValueAsString(user);
System.out.println("java类转换为json串：" + jsonStr);
User fromJson = objectMapper.readValue(jsonStr, User.class);
int id = fromJson.getId();
String username = fromJson.getUsername();
String password = fromJson.getPassword();
System.out.println(id +" : "+username + " : " + password);
}
@Test
public void test2() throws JsonProcessingException {
//集合转json串
User user1 = new User(1,"zhangsan", "111111");
User user2 = new User(2,"lisi", "222222");
List
users.add(user1);
users.add(user2);
System.out.println("初始化类：" + users);
//创建jackson对象
ObjectMapper objectMapper = new ObjectMapper();
String jsonStr = objectMapper.writeValueAsString(users);
System.out.println("java类转换为json串：" + jsonStr);
List list = objectMapper.readValue(jsonStr, List.class);
System.out.println(list);
for (int i = 0; i < list.size(); i++) {
Object obj = list.get(i);
String jsonStrs = objectMapper.writeValueAsString(obj);
User user = objectMapper.readValue(jsonStrs, User.class);
int id = user.getId();
String username = user.getUsername();
String password = user.getPassword();
System.out.println(id +" : "+username + " : " + password);
}
}
@Test
public void test3() throws JsonProcessingException {
//集合转json串
User user1 = new User(1,"zhangsan", "111111");
User user2 = new User(2,"lisi", "222222");
List
users.add(user1);
users.add(user2);
System.out.println("初始化类：" + users);
//复杂java类转换对象
UserGroup userGroup = new UserGroup("userGroup", users);
System.out.println("初始化类：" + userGroup);
//创建jackson对象
ObjectMapper objectMapper = new ObjectMapper();
String userGroupJson = objectMapper.writeValueAsString(userGroup);
System.out.println("复杂java类转换json串：" + userGroupJson);
UserGroup userGroupStr = objectMapper.readValue(userGroupJson, UserGroup.class);
String userGroupStrName = userGroupStr.getName();
List
System.out.println(userGroupStrName);
System.out.println(usersList);
for (int i = 0; i < usersList.size(); i++) {
Object obj = usersList.get(i);
String jsonStrs = objectMapper.writeValueAsString(obj);
User user = objectMapper.readValue(jsonStrs, User.class);
int id = user.getId();
String username = user.getUsername();
String password = user.getPassword();
System.out.println(id +" : "+username + " : " + password);
}
}
参考链接
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