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);

    }
}