MapStruct、ignore

文章目录

• • @[toc]
• 使用
• • 由Spring代理
  • 不由spring代理
• 其它属性
• • ignore
• 原理

Json工具是通过序列化反序列化来实现的，性能低下。

MapStruct是通过getter、setter来实现的。

        <!--MapStruct依赖-->
        <!-- https://mvnrepository.com/artifact/org.mapstruct/mapstruct-jdk8 -->
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-jdk8</artifactId>
            <version>1.0.0.Final</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mapstruct/mapstruct-processor -->
        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct-processor</artifactId>
            <version>1.0.0.Final</version>
        </dependency>

使用

@Data
@Builder
public class User {
    private String uname;
    private Integer uid;
    private String uaddr;
}

@Data
@Builder
@ToString
@AllArgsConstructor
@NoArgsConstructor
public class UserDto {

    private String name;
    private  Integer id;
    private Integer updateUserId;

}

由Spring代理

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.factory.Mappers;

@Mapper(componentModel = "spring")  //表示由Spring代理
public interface UserMapping {

    //UserMapping USERMAPOING = Mappers.getMapper(UserMapping.class);   //可以不要

/*
将user的uname映射成目标类userDto的name字段
...
*/
    @Mapping(target = "name",source = "uname")
    @Mapping(target = "id",source = "uid")
    UserDto userToUserDto(User user);
}

使用

    @Resource
    private UserMapping userMapping;
    
    public void func(){
         User user = User.builder()
                .uname("zhangsan")
                .uid(22)
                .build();

        UserDto userDto = userMapping.userToUserDto(user);
    }
    

---

不由spring代理

@Mapper
public interface UserMapping {

    UserMapping USERMAPOING = Mappers.getMapper(UserMapping.class);

    @Mapping(target = "name",source = "uname")
    @Mapping(target = "id",source = "uid")
    UserDto userToUserDto(User user);
}

    @Test
    public void t1(){

        User user = User.builder()
                .uname("zhangsan")
                .uid(22)
                .build();

        UserDto userDto = UserMapping.USERMAPOING.userToUserDto(user);
        userDto.setUpdateUserId(111);
        log.info(userDto.toString());
    }

---

其它属性

ignore

@Mapping(target = “age”, ignore = true)
添加了ignore，表示不会对该属性做映射；

---

原理

MapStruct生成了mapping的实现类，通过调用get\set实现；

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2021-04-30T12:58:59+0800",
    comments = "version: 1.0.0.Final, compiler: javac, environment: Java 1.8.0_211 (Oracle Corporation)"
)
@Component
public class UserMappingImpl implements UserMapping {

    @Override
    public UserDto userToUserDto(User user) {
        if ( user == null ) {
            return null;
        }

        UserDto userDto = new UserDto();

        userDto.setName( user.getUname() );
        userDto.setId( user.getUid() );

        return userDto;
    }
}