// 用戶實(shí)體類(lèi)
@Entity
@Table(name = "users")
public class UserEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String password;
    private String email;
    private String phoneNumber;
    private LocalDateTime createTime;
    private LocalDateTime updateTime;
    // getter和setter省略
}

// 用戶DTO類(lèi)
public class UserDTO {
    private Long id;
    private String username;
    private String email;
    private String phone; // 注意命名差異
    private LocalDateTime registerTime; // 映射自createTime
    // getter和setter省略
}

public class UserMapper {
    
    public static UserDTO toDTO(UserEntity entity) {
        if (entity == null) {
            return null;
        }
        
        UserDTO dto = new UserDTO();
        dto.setId(entity.getId());
        dto.setUsername(entity.getUsername());
        dto.setEmail(entity.getEmail());
        dto.setPhone(entity.getPhoneNumber()); // 不同名稱(chēng)字段映射
        dto.setRegisterTime(entity.getCreateTime()); // 語(yǔ)義轉(zhuǎn)換
        
        return dto;
    }
    
    public static UserEntity toEntity(UserDTO dto) {
        if (dto == null) {
            return null;
        }
        
        UserEntity entity = new UserEntity();
        entity.setId(dto.getId());
        entity.setUsername(dto.getUsername());
        entity.setEmail(dto.getEmail());
        entity.setPhoneNumber(dto.getPhone()); // 不同名稱(chēng)字段映射
        entity.setCreateTime(dto.getRegisterTime()); // 語(yǔ)義轉(zhuǎn)換
        
        return entity;
    }
    
    // 集合轉(zhuǎn)換方法
    public static List<UserDTO> toDTOList(List<UserEntity> entities) {
        if (entities == null) {
            return Collections.emptyList();
        }
        
        return entities.stream()
                .map(UserMapper::toDTO)
                .collect(Collectors.toList());
    }
}

<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct</artifactId>
    <version>1.5.3.Final</version>
</dependency>
<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct-processor</artifactId>
    <version>1.5.3.Final</version>
    <scope>provided</scope>
</dependency>

@Mapper(componentModel = "spring")
public interface UserMapStruct {
    
    @Mapping(source = "phoneNumber", target = "phone")
    @Mapping(source = "createTime", target = "registerTime")
    UserDTO toDTO(UserEntity entity);
    
    @Mapping(source = "phone", target = "phoneNumber")
    @Mapping(source = "registerTime", target = "createTime")
    UserEntity toEntity(UserDTO dto);
    
    List<UserDTO> toDTOList(List<UserEntity> entities);
    
    // 默認(rèn)值處理
    @Mapping(target = "email", defaultValue = "no-email@example.com")
    UserDTO toDTOWithDefaultEmail(UserEntity entity);
    
    // 自定義方法處理復(fù)雜轉(zhuǎn)換
    default String formatPhoneNumber(String phoneNumber) {
        if (phoneNumber == null || phoneNumber.trim().isEmpty()) {
            return null;
        }
        // 格式化電話號(hào)碼邏輯
        return phoneNumber.replaceAll("(\d{3})(\d{4})(\d{4})", "$1-$2-$3");
    }
}

@Service
public class UserService {
    
    private final UserMapStruct userMapper;
    
    @Autowired
    public UserService(UserMapStruct userMapper) {
        this.userMapper = userMapper;
    }
    
    public UserDTO getUserDTO(Long id) {
        UserEntity entity = userRepository.findById(id).orElseThrow();
        return userMapper.toDTO(entity);
    }
    
    public List<UserDTO> getAllUserDTOs() {
        List<UserEntity> entities = userRepository.findAll();
        return userMapper.toDTOList(entities);
    }
}

<dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
    <version>3.1.1</version>
</dependency>

@Configuration
public class ModelMapperConfig {
    
    @Bean
    public ModelMapper modelMapper() {
        ModelMapper modelMapper = new ModelMapper();
        
        // 配置映射策略
        modelMapper.getConfiguration()
                .setMatchingStrategy(MatchingStrategies.STRICT)
                .setPropertyCondition(Conditions.isNotNull())
                .setFieldAccessLevel(Configuration.AccessLevel.PRIVATE)
                .setFieldMatchingEnabled(true);
        
        // 自定義字段映射
        PropertyMap<UserEntity, UserDTO> userMap = new PropertyMap<UserEntity, UserDTO>() {
            @Override
            protected void configure() {
                map().setPhone(source.getPhoneNumber());
                map().setRegisterTime(source.getCreateTime());
            }
        };
        
        modelMapper.addMappings(userMap);
        
        return modelMapper;
    }
}

@Service
public class UserService {
    
    private final ModelMapper modelMapper;
    private final UserRepository userRepository;
    
    @Autowired
    public UserService(ModelMapper modelMapper, UserRepository userRepository) {
        this.modelMapper = modelMapper;
        this.userRepository = userRepository;
    }
    
    public UserDTO getUserDTO(Long id) {
        UserEntity entity = userRepository.findById(id).orElseThrow();
        return modelMapper.map(entity, UserDTO.class);
    }
    
    public List<UserDTO> getAllUserDTOs() {
        List<UserEntity> entities = userRepository.findAll();
        return entities.stream()
                .map(entity -> modelMapper.map(entity, UserDTO.class))
                .collect(Collectors.toList());
    }
    
    public UserEntity createUser(UserDTO dto) {
        UserEntity entity = modelMapper.map(dto, UserEntity.class);
        return userRepository.save(entity);
    }
}

import org.springframework.beans.BeanUtils;

public class UserMapperWithBeanUtils {
    
    public static UserDTO toDTO(UserEntity entity) {
        if (entity == null) {
            return null;
        }
        
        UserDTO dto = new UserDTO();
        // 復(fù)制相同名稱(chēng)的屬性
        BeanUtils.copyProperties(entity, dto);
        
        // 手動(dòng)處理不同名稱(chēng)的屬性
        dto.setPhone(entity.getPhoneNumber());
        dto.setRegisterTime(entity.getCreateTime());
        
        return dto;
    }
    
    public static UserEntity toEntity(UserDTO dto) {
        if (dto == null) {
            return null;
        }
        
        UserEntity entity = new UserEntity();
        BeanUtils.copyProperties(dto, entity);
        
        // 手動(dòng)處理不同名稱(chēng)的屬性
        entity.setPhoneNumber(dto.getPhone());
        entity.setCreateTime(dto.getRegisterTime());
        
        return entity;
    }
    
    public static List<UserDTO> toDTOList(List<UserEntity> entities) {
        if (entities == null) {
            return Collections.emptyList();
        }
        
        return entities.stream()
                .map(UserMapperWithBeanUtils::toDTO)
                .collect(Collectors.toList());
    }
}

import org.springframework.cglib.beans.BeanCopier;

public class UserMapperWithBeanCopier {
    
    // 創(chuàng)建并緩存BeanCopier實(shí)例，提高性能
    private static final BeanCopier ENTITY_TO_DTO = BeanCopier.create(UserEntity.class, UserDTO.class, false);
    private static final BeanCopier DTO_TO_ENTITY = BeanCopier.create(UserDTO.class, UserEntity.class, false);
    
    public static UserDTO toDTO(UserEntity entity) {
        if (entity == null) {
            return null;
        }
        
        UserDTO dto = new UserDTO();
        // 復(fù)制相同名稱(chēng)的屬性
        ENTITY_TO_DTO.copy(entity, dto, null);
        
        // 手動(dòng)處理不同名稱(chēng)的屬性
        dto.setPhone(entity.getPhoneNumber());
        dto.setRegisterTime(entity.getCreateTime());
        
        return dto;
    }
    
    public static UserEntity toEntity(UserDTO dto) {
        if (dto == null) {
            return null;
        }
        
        UserEntity entity = new UserEntity();
        DTO_TO_ENTITY.copy(dto, entity, null);
        
        // 手動(dòng)處理不同名稱(chēng)的屬性
        entity.setPhoneNumber(dto.getPhone());
        entity.setCreateTime(dto.getRegisterTime());
        
        return entity;
    }
}