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