FastJson的学习

fastjson是阿里巴巴的开源JSON解析库，它可以解析JSON格式的字符串，支持将Java Bean序列化为JSON字符串，也可以从JSON字符串反序列化到JavaBean。 fastjson是json的序列化和反序列化

一、添加依赖

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.83</version>
</dependency>

完整的pom文件如下所示:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.15</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>FastJsonDemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>FastJsonDemo</name>
    <description>FastJsonDemo</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.83</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.7.15</version>
            </plugin>
        </plugins>
    </build>

</project>

二、创建实体

package com.example.fastjsondemo.model;

import lombok.Data;

/**
 * @author qx
 * @date 2023/8/29
 * @des
 */
@Data
public class Student {

    private Long id;
    private String name;
    private Integer age;

}

package com.example.fastjsondemo.model;

import lombok.Data;

/**
 * @author qx
 * @date 2023/8/29
 * @des
 */
@Data
public class School {
    private String name;
    private String address;
}

三、测试

将对象生成json

  /**
     * 将一个对象转成Json
     */
    @Test
    void testToJson() {
        Student student = new Student();
        student.setId(1L);
        student.setName("qx");
        student.setAge(20);
        String json = JSONObject.toJSONString(student);
        // 输出{"age":20,"id":1,"name":"qx"}
        System.out.println(json);
    }

json转对象

    /**
     * json转对象
     */
    @Test
    void testToObject() {
        String data = "{\"age\":20,\"id\":1,\"name\":\"qx\"}";
        Student student = JSONObject.parseObject(data, Student.class);
        // 输出Student(id=1, name=qx, age=20)
        System.out.println(student);
    }

根据键获取Json数据中的值

   /**
     * 获取json中的值
     */
    @Test
    void testAccessValue() {
        String data = "{\"age\":20,\"id\":1,\"name\":\"qx\"}";
        JSONObject jsonObject = JSONObject.parseObject(data);
        String name = jsonObject.getString("name");
        // 输出qx
        System.out.println(name);
        int age = jsonObject.getIntValue("age");
        // 输出20
        System.out.println(age);

    }

四、实体类中存在其他对象的情况

package com.example.fastjsondemo.model;

import lombok.Data;

/**
 * @author qx
 * @date 2023/8/29
 * @des
 */
@Data
public class Student {

    private Long id;
    private String name;
    private Integer age;
    private School school;

}

测试

对象转Json

 @Test
    void testToJson() {
        Student student = new Student();
        student.setId(1L);
        student.setName("qx");
        student.setAge(20);

        School school = new School();
        school.setName("广西大学");
        school.setAddress("南宁西乡塘区");
        student.setSchool(school);
        String json = JSONObject.toJSONString(student);
        // 输出{"age":20,"id":1,"name":"qx","school":{"address":"南宁西乡塘区","name":"广西大学"}}
        System.out.println(json);
    }

Json转对象

  /**
     * json转对象
     */
    @Test
    void testToObject() {
        String data = "{\"age\":20,\"id\":1,\"name\":\"qx\",\"school\":{\"address\":\"南宁西乡塘区\",\"name\":\"广西大学\"}}";
        Student student = JSONObject.parseObject(data, Student.class);
        // 输出Student(id=1, name=qx, age=20, school=School(name=广西大学, address=南宁西乡塘区))
        System.out.println(student);
    }

获取Json中的某个值

    /**
     * 获取json中的值
     */
    @Test
    void testAccessValue() {
        String data = "{\"age\":20,\"id\":1,\"name\":\"qx\",\"school\":{\"address\":\"南宁西乡塘区\",\"name\":\"广西大学\"}}";
        JSONObject jsonObject = JSONObject.parseObject(data);
        JSONObject school = jsonObject.getJSONObject("school");
        String name = school.getString("name");
        // 输出 广西大学
        System.out.println(name);

    }