MapStruct

1. Dependency

   • https://mvnrepository.com/artifact/org.mapstruct/mapstruct-jdk8/1.3.1.Final
   • https://mvnrepository.com/artifact/org.mapstruct/mapstruct-processor

2. 기능

   • Entity와 DTO, VO의 객체를 Convert 해주는 Mapper를 생성한다.

3. 설정

       - build.gradle
   
       plugins {
           ...
           id 'net.ltgt.apt' version '0.20'
       }
   
       allprojects {
           ...
           apply plugin: 'net.ltgt.apt-idea'
           apply plugin: 'net.ltgt.apt-eclipse'
       }
   
       subprojects {
           ...
           dependencies {
               ...
               implementation (
                       ...
                       "org.mapstruct:mapstruct:${mapstructVersion}"
               )
   
               compileOnly (
               	    ...
                       "org.projectlombok:lombok:${lombokVersion}"
               )
   
               annotationProcessor(
                       ...
                       "org.projectlombok:lombok:${lombokVersion}",
                       "org.mapstruct:mapstruct-processor:${mapstructVersion}"
               )
           }
   
           ...
           compileJava {
               options.compilerArgs = [
                       '-Amapstruct.suppressGeneratorTimestamp=true',
                       '-Amapstruct.suppressGeneratorVersionInfoComment=true'
               ]
           }
       }
   
       - lombok.config: mapStruct에서 lombok의 builder를 사용하기 위해 project root에 추가.
       lombok.addLombokGeneratedAnnotation = true
       lombok.anyConstructor.addConstructorProperties = true

4. Entity & DTO

        - MapStruct는 기본적으로 setter를 사용하여 값을 추가한다. 
        하지만 immutable이 아니기 때문에 lombok의 Builder를 사용했다.
   
        @Getter
        @Builder
        @ToString
        public class Address {
            private String address1;
            private String address2;
            private String address3;
        }
   
        @Getter
        @Builder
        @ToString
        public class Member {
            private Long id;
            private String name;
            private Integer age;
            private Address address;
            private String phoneNumber;
            private String email;
        }
   
        @Getter
        @Builder
        @ToString
        public class MemberDto {
            private String memberName;
            private Integer age;
            private Address address;
            private String phoneNumber;
            private String email;
        }

5. Mapper Interface & generated impl

       - Mapper Interface
       @Mapper
       public interface MemberMapper {
           MemberMapper INSTANCE = Mappers.getMapper(MemberMapper.class);
   
           @Mapping(source = "member.name", target = "memberName")
           MemberDto memberToMemberDto(Member member);
   
           @Mapping(source = "memberDto.memberName", target = "name")
           Member memberToMemberDto(MemberDto memberDto, Long id);
       }
   
       - Generated Impl
       @Generated(
           value = "org.mapstruct.ap.MappingProcessor"
       )
       public class MemberMapperImpl implements MemberMapper {
   
           @Override
           public MemberDto memberToMemberDto(Member member) {
               if ( member == null ) {
                   return null;
               }
   
               MemberDtoBuilder memberDto = MemberDto.builder();
   
               memberDto.name( member.getName() );
               memberDto.age( member.getAge() );
               memberDto.address( member.getAddress() );
               memberDto.phoneNumber( member.getPhoneNumber() );
               memberDto.email( member.getEmail() );
   
               return memberDto.build();
           }
   
           @Override
           public Member memberToMemberDto(MemberDto memberDto, Long id) {
               if ( memberDto == null && id == null ) {
                   return null;
               }
   
               MemberBuilder member = Member.builder();
   
               if ( memberDto != null ) {
                   member.name( memberDto.getName() );
                   member.age( memberDto.getAge() );
                   member.address( memberDto.getAddress() );
                   member.phoneNumber( memberDto.getPhoneNumber() );
                   member.email( memberDto.getEmail() );
               }
               if ( id != null ) {
                   member.id( id );
               }
   
               return member.build();
           }
       }

6. Test

       public class MemberMapperLauncher {
         public static void main(String[] args) {
             Address address = Address.builder()
                 .address1("kor")
                 .address2("seoul")
                 .address3("gangnam")
                 .build();
   
             Member member = Member.builder()
                 .id(1L)
                 .name("jack")
                 .age(20)
                 .address(address)
                 .phoneNumber("010-1234-1234")
                 .email("abcd@google.com")
                 .build();
   
             MemberDto memberDto = MemberMapper.INSTANCE.memberToMemberDto(member);
             System.out.println(memberDto);
             //MemberDto(name=jack, age=20, address=base.domain.example.mapstruct.Address@4edde6e5, phoneNumber=010-1234-1234, email=abcd@google.com)
   
             Member member1 = MemberMapper.INSTANCE.memberToMemberDto(memberDto, 1234L);
             System.out.println(member1);
             //Member(id=1234, name=jack, age=20, address=Address(address1=kor, address2=seoul, address3=gangnam), phoneNumber=010-1234-1234, email=abcd@google.com)
     }
   }

7. 심화

   • @Mapper Annotaion에서 지원하는 detail settings

     

     

   • @Mapping Annotaion에서 지원하는 detail settings

     

   • @MapperConfig(componentModel = "spring" ...)을 사용하면 Spring 사용시 Mapper를 Bean으로 등록해준다. 나머지 상세 설정은 레퍼런스 페이지를 참고한다.

8. Reference:

   1. https://mapstruct.org/documentation/stable/reference/html/#basic-mappings
   2. https://www.baeldung.com/mapstruct
   3. https://mapstruct.org/documentation/1.0/reference/html/#implicit-type-conversions
   4. https://blog.jdriven.com/2019/07/mapstruct-and-lombok
   5. https://meetup.toast.com/posts/213