Json字符串与Object对象相互转换的几种方式

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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

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