java - 在 Spring Boot 中，某些字段未在 JSON 中被解析/反序列化

Question

我正在使用以下 JSON 由我的 springboot 代码解析:

{
    "id" :123, 
    "Subject" : "English",
    "name": {
    "Firstname": "Hemant",
    "Middlename": "kumar", 
    "Lastname": "Mamod"
    }
}

但是在解析/反序列化它时，我在 Student 的对象中得到了这个:

Student [id=123, Subject=null, name=Name [Firstname=null, Middlename=null, Lastname=null]]

我已经到处都有公共(public) getters 和 setters，这使得每个字段都有资格进行反序列化。我指的是这个 - https://www.baeldung.com/jackson-field-serializable-deserializable-or-not

下面是我使用的代码片段:

休息 Controller :

    package com.example.demo;
    import java.util.*;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.http.MediaType;
    import org.springframework.web.bind.annotation.*;


    @SpringBootApplication
    @RestController
    public class Demo1Application {


    @Autowired
    Student student;
    List<Student> students = new ArrayList<>();


    @RequestMapping(value="/saveStudent", method=RequestMethod.POST,consumes=MediaType.APPLICATION_JSON_VALUE)
    public String savestudent (@RequestBody Student s1) {

        System.out.println(s1);
        return "success";
    }   


    public static void main(String[] args) {
        SpringApplication.run(Demo1Application.class, args);
        System.out.println("Hello");
    }
    }

学生 Bean 类:

package com.example.demo;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

@Component
public class Student {
    int id;
    String Subject;

    @Autowired
    @Qualifier("name")
    Name name;


    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getSubjects() {
        return Subject;
    }
    public void setSubject(String subject) {
        Subject = subject;
    }

    public void setName(Name name) {
        this.name = name;  
    }
    public Name getName() {  
        return name  ;
    }
@Override
public String toString() {
    return "Student [id=" + id + ", Subject=" + Subject + ", name=" + name + "]";
    }
}

命名 Bean 类:

package com.example.demo;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

@Component
@Qualifier("name")
public class Name {
    private String Firstname;
    private String Middlename;
    private String Lastname;

    public Name() {
        System.out.println("Name Object created");
    }

    public String getFirstname() {
        return Firstname;
    }
    public void setFirstname(String firstname) {
        Firstname = firstname;
    }
    public String getMiddlename() {
        return Middlename;
    }
    public void setMiddlename(String middlename) {
        Middlename = middlename;
    }
    public String getLastname() {
        return Lastname;
    }
    public void setLastname(String lastname) {
        Lastname = lastname;
    }

    public Name setfullname(String Fname, String Mname, String Lname) {
        Firstname = Fname;
        Middlename = Mname;
        Lastname = Lname;
        return this;
    }

    @Override
    public String toString() {
        return "Name [Firstname=" + Firstname + ", Middlename=" + Middlename + ", Lastname=" + Lastname + "]";
    }

}

附言-

1.) On making the private fields as public , the code is working fine. I made these fields as public - id , Subject , name, Firstname, Middlename, Lastname

2.) I already know that by adding below two in application.properties wil give me correct output: spring.jackson.deserialization.fail-on-unknown-properties=false spring.jackson.mapper.accept-case-insensitive-properties=true

我只想知道我到底哪里做错了。我到处都有公共(public) gettters & setter

Answer 1

使用@JsonProperty注解将json中的属性名映射到java中的属性名:

@JsonProperty("Firstname")
private String firstname;
@JsonProperty("Middlename")
private String middlename;
@JsonProperty("Lastname")
private String lastname;