@Component
public class UserService {
public String getUserName(Long id) {
return "User " + id;
}
}
使用 @Service ：
@Service
public class UserService {
private final UserRepository userRepository;
public UserService(UserRepository userRepository) {
this.userRepository = userRepository;
}
public User findById(Long id) {
return userRepository.findById(id)
.orElseThrow(() -> new UserNotFoundException(id));
}
}
@RestController
@RequestMapping("/api/users")
public class UserController {
private final UserService userService;
public UserController(UserService userService) {
this.userService = userService;
}
@GetMapping
public List<User> getAllUsers() {
return userService.findAll();
}
@GetMapping("/{id}")
public User getUserById(@PathVariable Long id) {
return userService.findById(id);
}
@PostMapping
public User createUser(@RequestBody User user) {
return userService.save(user);
}
@PutMapping("/{id}")
public User updateUser(@PathVariable Long id, @RequestBody User user) {
return userService.update(id, user);
}
@DeleteMapping("/{id}")
public void deleteUser(@PathVariable Long id) {
userService.delete(id);
}
}
异常处理 ：
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(UserNotFoundException.class)
public ResponseEntity<ErrorResponse> handleUserNotFound(UserNotFoundException ex) {
ErrorResponse error = new ErrorResponse(
HttpStatus.NOT_FOUND.value(),
ex.getMessage()
);
return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
}
}
5. 数据访问
JPA Entity ：
@Entity
@Table(name = "users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(nullable = false)
private String name;
@Column(unique = true, nullable = false)
private String email;
// Getters and Setters
}
Repository ：
@Repository
public interface UserRepository extends JpaRepository<User, Long> {
Optional<User> findByEmail(String email);
List<User> findByNameContaining(String name);
@Query("SELECT u FROM User u WHERE u.email = :email")
Optional<User> findByEmailCustom(@Param("email") String email);
}
Service ：
@Service
@Transactional
public class UserService {
private final UserRepository userRepository;
public UserService(UserRepository userRepository) {
this.userRepository = userRepository;
}
public User save(User user) {
return userRepository.save(user);
}
public Optional<User> findById(Long id) {
return userRepository.findById(id);
}
public List<User> findAll() {
return userRepository.findAll();
}
public void delete(Long id) {
userRepository.deleteById(id);
}
}
6. 配置管理
@ConfigurationProperties ：
@ConfigurationProperties(prefix = "app")
@Data
public class AppProperties {
private String name;
private String version;
private Database database;
@Data
public static class Database {
private String host;
private int port;
private String name;
}
}
