java-Spring Hibernate没有获取参数的值

我尝试通过邮递员使用post方法对我的spring boot应用程序进行API调用.
这是输入：

{
  "username": "name","password": "1234","age": 12,"salary": 5000,"role": 1
}

这是控制器中的代码：

@RequestMapping(value = "/signup",method = RequestMethod.POST,consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<?> saveUser(@RequestBody UserDto user) {
        try {
            System.out.println(user.getUsername()); // => name
            System.out.println(user.getPassword()); // => 1234
            System.out.println(user.getSalary()); // => 5000
            System.out.println(user.getRole()); // => 1
            System.out.println(user.getAge()); // => 12
            userService.save(user);
            return ResponseEntity.ok().body("insert done");
        } catch (Exception e) {
            return ResponseEntity.badRequest().body(e.getMessage());
        }
    }

这是我的User.java

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column
private String username;
@Column
@JsonIgnore
private String password;
@Column
private long salary;
@Column
private int age;
@ManyToOne(fetch = FetchType.LAZY,optional = false)
@JoinColumn(name = "role_id")
private Role role;
// getters and setters

这是我的Role.java

@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Column(name = "role_name",nullable = false)
private String roleName;
// getters and setters

这是我的UserDto.java

private String username;
private String password;
private int age;
private long salary;
private int role;
// getters and setters

这是我的RoleDto.java

private Long id;
private String roleName;
// getters and setters

问题：它引发错误“列’role_id’不能为空”

这是在userServiceImpl中：
第(BeanUtils)行下方是here.

    @Override
    public User save(UserDto user) throws Exception {
        User newUser = new User();
        BeanUtils.copyProperties(user,newUser,"password");
        newUser.setPassword(bcryptEncoder.encode(user.getPassword()));
        try {
            userDao.save(newUser);
        } catch (Exception e) {
            throw new Exception(e);
            // this throw "Column role_id cannot be null"
        }
        return newUser;
    }

但是,如果我使用以下代码,则setRole方法不适用,因为我在DTO中将user.getRole()定义为int,但在User实体中将newUser.setRole()定义为Role.但是,如果我将User实体中的setRole更改为int,那我该如何告诉用户和角色之间的ManyToOne关系呢？

@Override
public User save(UserDto user) throws Exception {
    User newUser = new User();
    newUser.setUsername(user.getUsername());
    newUser.setPassword(bcryptEncoder.encode(user.getPassword()));
    newUser.setAge(user.getAge());
    newUser.setSalary(user.getSalary());
    newUser.setRole(user.getRole()); // here is the problem
    try {
        userDao.save(newUser);
    } catch (Exception e) {
        throw new Exception(e);
    }
    return newUser;
}

注意：我想我只想使角色的输入参数只是上面提供的整数.