Question

我有一门学生课，但领域很少。由于某种原因，我没有在Student对象中创建“创建的”对象。当我发送GET调用以接收所有学生对象的信息时，我仅看到前四个参数。缺少创建的字段。我想念什么？

在学生构造函数中，我定义了“ this.created = new Date（）;”。为创建的字段分配值。

 public class Student {

    private String firstName;
    private String lastName;
    private String address;
    private String enrolledDepartment;
    private Date created;

    public Student() {          
    }

    public Student(String firstName, String lastName, String address, String departmentName){
        this.firstName = firstName;
        this.lastName = lastName;
        this.address = address;
        this.enrolledDepartment = departmentName;
        this.created = new Date();
    }

   // Getter and setters of all fields
}

资源类

@Path("/students")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public class StudentsResource {

    List<Student> students = new ArrayList<>();
    private StudentService studentService = new StudentService();

    @GET
    public List<Student> getProfiles() {
        return studentService.getAllStudents();
    }

    @POST
    public Student addProfile(Student profile) {
        return studentService.addProfile(profile);
    }
}

服务类别

public class StudentService {

    private List<Student> students = DatabaseClass.getStudents();

    public List<Student> getAllStudents() {
        return students; 
    }

    public Student addProfile(Student student) {
        students.add(student);
        return student;
    }
}

数据库类

public class DatabaseClass {

    private static List<Student> students = new ArrayList<>();
    private static List<Email> emails = new ArrayList<>();

    public static List<Student> getStudents() {
        return students;
    }

    public static List<Email> getEmails() {
        return emails;
    }
}

我正在使用以下JSON发送POST请求

{
    "address": "Boston",
    "enrolledDepartment": "health",
    "firstName": "abc",
    "lastName": "pqr"
}

Answer 1

将其添加到“默认构造函数”：

 public Student() {
    this.created = new Date();          
 }

...假定您未调用的构造函数，因此created仍为null。

甚至：

// ...
private Date created = new Date();

public Student() {          
}

public Student(String firstName, String lastName, String address, String departmentName){
    this.firstName = firstName;
    this.lastName = lastName;
    this.address = address;
    this.enrolledDepartment = departmentName;
    //this.created = new Date();
}

（在声明中将其初始化。）

无法打印REST对象中的所有参数

1 个答案: