java - Springboot API 返回空响应

Question

我构建了一个简单的 Springboot API，它连接到包含一些测试数据的 H2 数据库。但是，当我访问 API 端点时，我得到一个空响应。

[{}]

当我调试我的应用程序时， Controller 返回的用户对象包含我期望的用户。

用户 Controller .java

@RestController
@RequestMapping("api/user")
public class UserController {

    private UserService userService;

    public UserController(@Autowired UserService userService){
        this.userService = userService;
    }

    @GetMapping(produces = MediaType.APPLICATION_JSON_VALUE)
    public Set<User> getAllUsers(){
        final Set<User> users = userService.getAllUsers();
        return users;
    }
}

用户库.java

public interface UserRepository extends CrudRepository<User, Long> {

    @Query("SELECT usr from User usr")
    Set<User> getAllUsers();
}

用户服务.java

public interface UserService {

    Set<User> getAllUsers();
}

UserServiceImpl.java

@Service
public class UserServiceImpl implements UserService {

    private final UserRepository repository;

    public UserServiceImpl(@Autowired UserRepository userRepository){
        this.repository = userRepository;
    }

    @Override
    public Set<User> getAllUsers(){
        final Set<User> users = repository.getAllUsers();
        return users;
    }
}

用户.java

@Entity
@Getter
public class User {

    @Id
    private Long id;
    private String username;
    private String firstname;
    private String lastname;
    private String email;
    private String role;
    private String premium;
}

Answer 1

您必须将 User 的类成员设置为 public 以允许 jackson 序列化它们，即

// User.java
@Entity
public class User {
    @Id
    public Long id;
    public String username;
    public String firstname;
    public String lastname;
    public String email;
    public String role;
    public String premium;
}

注意:如果您不想序列化某个字段，请使用@JsonIgnore 而不是将其设置为私有(private)，例如<​​/p>

@Entity
public class User {
    ...
    @JsonIgnore
    public String role;
    ...
}