我遇到如下所示代码的问题。下面的代码生成 json 如下:
[{"id":123,"subjects":"English"},{"id":456,"subjects":"Maths"}]
我们可以看到生成的 JSON 中缺少名称标签。我不明白当我返回学生列表时,生成的 json 应该包含名称标签,因为学生类中有一个类型为“名称”的属性。请帮忙!
PS:我已经在调试中获取了代码,并且我看到“students arraylist”0索引和索引确实包含名称prpoperty以及id和主题。但 JSON 不包含此属性。
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="/getStudents", method=RequestMethod.GET,produces=MediaType.APPLICATION_JSON_VALUE)
public List<Student> getstudent () {
students = student.setStudent();
return students;
}
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(String Fname, String Mname, String Lname) {
Name nm = new Name();
name = nm.setfullname(Fname,Mname,Lname) ;
}
public Student(int id, String Subject) {
this.id = id;
this.Subject = Subject;
}
public Student() {
System.out.println("Student Object created");
}
public List<Student> setStudent() {
List<Student> Students = new ArrayList<>();
Student s = new Student ();
Student s1 = new Student ();
s.setId(123);
s.setSubject("English");
s.setName("Hemant", "123", "Mamod");
s1.setId(456);
s1.setSubject("Maths");
s1.setName("Akshay", "123", "pandey");
Students.add(s);
Students.add(s1);
return Students;
}
}
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 {
String Firstname;
String Middlename;
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;
}
}
最佳答案
问题是您在 Student
类中没有 Name
的 getter。
请添加 getter,如下所示:
@Component
public class Student {
int id;
String Subject;
Name name;
/******/
public Name getName() {
return name;
}
}
谈到具有 name
属性的 NullPinterException
- 这意味着它由于某些原因尚未 Autowiring ,因此在您的情况下,您可以删除 @Autowired
和 @Qualifier
注释或找出 Autowiring 的问题
关于java - springboot 生成的 JSON 中缺少名称标签,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52909661/