Json字符串与Object对象相互转换的几种方式

Json-Lib、Org.Json、Jackson、Gson、FastJson五种方式转换json类型

只列举了最省事的方式。不涉及复制情况和速度。

测试用例，一个User类，属性name，age，location。重写toString()。

public class User { private String name; private Integer age; private String location; public User() { } public User(String name) { this.name = name; } public User(String name, Integer age) { this.name = name; this.age = age; } public User(String name, Integer age, String location) { this.name = name; this.age = age; this.location = location; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } @Override public String toString() { return "User{" + "name='" + name + '\'' + ", age=" + age + ", location='" + location + '\'' + '}'; } }

1、Json-Lib

maven依赖如下，需注意<classifier>jdk15</classifier>，jar包区分jdk1.3和jdk1.5版本

<dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.4</version> <classifier>jdk15</classifier> </dependency>

测试demo

import net.sf.json.JSONObject; public class JsonLibDemo { public static void main(String[] args) { //创建测试object User user = new User("李宁",24,"北京"); System.out.println(user); //转成json字符串 JSONObject jsonObject = JSONObject.fromObject(user); String json = jsonObject.toString(); System.out.println(json); //json字符串转成对象 JSONObject jsonObject1 = JSONObject.fromObject(json); User user1 = (User) JSONObject.toBean(jsonObject1,User.class); System.out.println(user1); } }

2、org.json

maven依赖如下

<dependency> <groupId>org.json</groupId> <artifactId>json</artifactId> <version>20170516</version> </dependency>

测试demo

import org.json.JSONObject; public class OrgJsonDemo { public static void main(String[] args) { //创建测试object User user = new User("李宁",24,"北京"); System.out.println(user); //转成json字符串 String json = new JSONObject(user).toString(); System.out.println(json); //json字符串转成对象 JSONObject jsonObject = new JSONObject(json); String name = jsonObject.getString("name"); Integer age = jsonObject.getInt("age"); String location = jsonObject.getString("location"); User user1 = new User(name,age,location); System.out.println(user1); } }

3、Jackson

maven依赖

<dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.9.0</version> </dependency>

测试demo

import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonDemo { public static void main(String[] args) { //创建测试object User user = new User("李宁",24,"北京"); System.out.println(user); //转成json字符串 ObjectMapper mapper = new ObjectMapper(); try { String json = mapper.writeValueAsString(user); System.out.println(json); //json字符串转成对象 User user1 = mapper.readValue(json,User.class); System.out.println(user1); } catch (java.io.IOException e) { e.printStackTrace(); } } }

4、Gson

maven依赖

<dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.8.1</version> </dependency>

测试demo

import com.google.gson.Gson; public class GsonDemo { public static void main(String[] args) { //创建测试object User user = new User("李宁",24,"北京"); System.out.println(user); //转成json字符串 Gson gson = new Gson(); String json = gson.toJson(user); System.out.println(json); //json字符串转成对象 User user1 = gson.fromJson(json,User.class); System.out.println(user1); } }

5、FastJson

maven依赖

<dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.37</version> </dependency>

测试demo

import com.alibaba.fastjson.JSON; public class FastJsonDemo { public static void main(String[] args) { //创建测试object User user = new User("李宁",24,"北京"); System.out.println(user); //转成json字符串 String json = JSON.toJSON(user).toString(); System.out.println(json); //json字符串转成对象 User user1 = JSON.parseObject(json,User.class); System.out.println(user1); } }

json-lib时间有些久远，jar包只更新到2010年

org.json用起来有些繁琐

Jackson、Gson、FastJson只需一两句话就可以搞定