@JsonProperty的使用

jackson的maven依赖

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.5.3</version>
</dependency>

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@JsonProperty 此注解用于属性上，作用是把该属性的名称序列化为另外一个名称，如把trueName属性序列化为name，@JsonProperty(value="name")。

import com.fasterxml.jackson.annotation.JsonProperty;
 
public class Student {
 
    @JsonProperty(value = "real_name")
    private String realName;
 
    public String getRealName() {
        return realName;
    }
 
    public void setRealName(String realName) {
        this.realName = realName;
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "realName='" + realName + '\'' +
                '}';
    }
}

测试

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
 
public class Main {
    public static void main(String[] args) throws JsonProcessingException {
        Student student = new Student();
        student.setRealName("zhangsan");
        System.out.println(new ObjectMapper().writeValueAsString(student));
    }
}

结果

{"real_name":"zhangsan"}

这里需要注意的是将对象转换成json字符串使用的方法是fasterxml.jackson提供的！！

如果使用fastjson呢？

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.28</version>
</dependency>

import com.alibaba.fastjson.JSON;
 
public class Main {
    public static void main(String[] args) {
        Student student = new Student();
        student.setRealName("zhangsan");
        System.out.println(JSON.toJSONString(student));
    }
}

结果

{"realName":"zhangsan"}

可以看到，@JsonProperty(value = "real_name")没有生效，为啥？

因为fastjson不认识@JsonProperty注解呀！所以要使用jackson自己的序列化工具方法！

--------------------------

@JsonProperty不仅仅是在序列化的时候有用，反序列化的时候也有用，比如有些接口返回的是json字符串，命名又不是标准的驼峰形式，在映射成对象的时候，将类的属性上加上@JsonProperty注解，里面写上返回的json串对应的名字

import com.fasterxml.jackson.databind.ObjectMapper;
 
import java.io.IOException;
 
public class Main {
    public static void main(String[] args) throws IOException {
        String jsonStr = "{\"real_name\":\"zhangsan\"}";
        Student student = new ObjectMapper().readValue(jsonStr.getBytes(), Student.class);
        System.out.println(student);
    }
}

结果：

Student{realName='zhangsan'}