import jakarta.persistence.*;
import lombok.Data;
import java.time.LocalDateTime;
// 與數(shù)據(jù)庫表user映射
@Entity
@Table(name = "user")
@Data // Lombok注解，自動生成getter、setter等
public class UserEntity {
    // 主鍵
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    // 用戶名，對應表中username字段
    private String username;
    // 密碼（加密存儲），對應表中password字段
    private String password;
    // 郵箱，對應表中email字段
    private String email;
    // 創(chuàng)建時間，對應表中create_time字段
    @Column(name = "create_time")
    private LocalDateTime createTime;
}

import lombok.Data;
import jakarta.validation.constraints.NotBlank;
import jakarta.validation.constraints.Email;
@Data
public class UserRegisterDTO {
    // 用戶名不能為空
    @NotBlank(message = "用戶名不能為空")
    private String username;
    // 密碼不能為空
    @NotBlank(message = "密碼不能為空")
    private String password;
    // 郵箱格式要正確
    @NotBlank(message = "郵箱不能為空")
    @Email(message = "郵箱格式不正確")
    private String email;
}

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;
    public void register(UserRegisterDTO registerDTO) {
        // 1. DTO轉(zhuǎn)換為Entity
        UserEntity userEntity = new UserEntity();
        userEntity.setUsername(registerDTO.getUsername());
        // 密碼加密（實際開發(fā)中一定要加密?。?
        userEntity.setPassword(encryptPassword(registerDTO.getPassword()));
        userEntity.setEmail(registerDTO.getEmail());
        userEntity.setCreateTime(LocalDateTime.now());
        // 2. 保存到數(shù)據(jù)庫
        userRepository.save(userEntity);
    }
    // 密碼加密方法（示例）
    private String encryptPassword(String rawPassword) {
        return new BCryptPasswordEncoder().encode(rawPassword);
    }
}

import lombok.Data;
@Data
public class UserVO {
    private Long id;
    private String username;
    private String email;
    // 可以增加前端需要的組合字段，比如"用戶標簽"
    private String userTag;
}

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;
    public UserVO getUserDetail(Long userId) {
        // 1. 從數(shù)據(jù)庫查詢Entity
        UserEntity userEntity = userRepository.findById(userId)
                .orElseThrow(() -> new RuntimeException("用戶不存在"));
        // 2. Entity轉(zhuǎn)換為VO
        UserVO userVO = new UserVO();
        userVO.setId(userEntity.getId());
        userVO.setUsername(userEntity.getUsername());
        userVO.setEmail(userEntity.getEmail());
        // 定制前端需要的組合字段
        userVO.setUserTag("普通用戶");
        return userVO;
    }
}

@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;
    @GetMapping("/{userId}")
    public UserVO getUserDetail(@PathVariable Long userId) {
        return userService.getUserDetail(userId);
    }
}

// 1. 引入依賴
<dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
    <version>3.2.0</version>
</dependency>
// 2. 配置Bean
@Configuration
public class ModelMapperConfig {
    @Bean
    public ModelMapper modelMapper() {
        return new ModelMapper();
    }
}
// 3. 服務中使用
@Service
public class UserService {
    @Autowired
    private ModelMapper modelMapper;
    public UserVO getUserDetail(Long userId) {
        UserEntity userEntity = userRepository.findById(userId).orElseThrow(...);
        // 自動轉(zhuǎn)換Entity到VO
        return modelMapper.map(userEntity, UserVO.class);
    }
}