FastJson使用

2024-08-23 11:44

文章标签 使用 fastjson

本文主要是介绍FastJson使用，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

FastJson

引入依赖

<dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.47</version>
</dependency>

序列化

使用的实体类和统一结果类在文章末尾

将User对象转化为json字符串

@Testvoid contextLoads() {User user = new User();String[] hobbies = {"sing","dance","rap"};user.setId(1L);user.setUsername("kunkun");user.setAge(22);user.setHobbies(hobbies);user.setRegisterDate(new Date());user.setBirthday(LocalDateTime.now());String toJSONString = JSON.toJSONString(user);System.out.println(toJSONString);}

最后输出结果为：

{“age”:22,“birthday”:1723649279811,“hobbies”:[“sing”,“dance”,“rap”],“registerDate”:1723649279811,“username”:“kunkun”}

对null值的处理
fastjson默认会将值为null的数据留空，如果想要对没有值的数据赋为null时可以添加一个参数

//对于对象中包含null值时
String toJSONString = JSON.toJSONString(user, SerializerFeature.WriteMapNullValue);

对日期的格式化

//对实体类修改
//fastjson序列化日期格式
@JSONField(format = "yyyy-MM-dd HH:mm:ss")
private Date registerDate;@JSONField(format = "yyyy-MM-dd HH:mm:ss")
private LocalDateTime birthday;

$Ref引用探测

@Test
void Test$Ref() {ArrayList<User> userList = new ArrayList<>();User user = new User();user.setId(1L);user.setUsername("zhangsan");user.setAge(22);userList.add(user);userList.add(user);userList.add(user);//直接打印输出结果为：[{"age":22,"id":1,"username":"zhangsan"},{"$ref":"$[0]"},{"$ref":"$[0]"}]//String json = JSON.toJSONString(userList);//禁用引用探测功能String json = JSON.toJSONString(userList,SerializerFeature.DisableCircularReferenceDetect);//会发现结果变为正常System.out.println(json);
}

对于SerializerFilter定制处理，等用到再学

反序列化

普通反序列化

@Test
void FastJsonSerializerFilter(){String json = "{\"age\":22,\"birthday\":\"2024-08-14 23:36:47\",\"hobbies\":[\"sing\",\"dance\",\"rap\"],\"id\":null,\"registerDate\":\"2024-08-14 23:36:47\",\"username\":\"kunkun\"}";//反序列化为user对象User user = JSON.parseObject(json, User.class);//User(id=null, username=kunkun, age=22, hobbies=[sing, dance, rap], registerDate=Wed Aug 14 23:36:47 CST 2024, birthday=2024-08-14T23:36:47)System.out.println(user);
}

遇到泛型，的解决方式
例如统一给调用端返回Result类，并且Result中采用了泛型data

String resultJson = "{\"code\":200,\"data\":{\"age\":22,\"birthday\":\"2024-08-14 23:56:34\",\"hobbies\":[\"sing\",\"dance\",\"rap\"],\"id\":null,\"registerDate\":\"2024-08-14 23:56:34\",\"username\":\"kunkun\"},\"msg\":\"null\"}\n";Result result = JSON.parseObject(resultJson, Result.class);
//再进行反序列化时，默认只能返回Object类型，需要进行强制类型转换
Object data = result.getData();//可以使用TypeReference
Result<User> o = JSON.parseObject(resultJson, new TypeReference<Result<User>>() {
});
User data1 = o.getData();

通用配置

写上在序列化或反序列化时都会生效

//指定属性名和json字符串key的对应关系
@JSONField( name = "address")
private String addr;//不参与序列化，与反序列化
@JSONField( serialize = fales , deserialize = false)
private String password;

使用到的类

import com.alibaba.fastjson.annotation.JSONField;
import lombok.Data;import java.time.LocalDateTime;
import java.util.Date;@Data
public class User {private Long id;private String username;private int age;private String[] hobbies;//fastjson序列化日期格式@JSONField(format = "yyyy-MM-dd HH:mm:ss")private Date registerDate;@JSONField(format = "yyyy-MM-dd HH:mm:ss")private LocalDateTime birthday;}

package com.sst.result;import lombok.Data;@Data
public class Result<T> {private int code;private String msg;private T data;public Result(int code, String msg, T t) {this.code = code;this.msg = msg;this.data = t;}
}