Spring REST : MapStuct

1. MapStuct은 lombok과 유사하게 동작하는 코드를 생성해 주는 라이브러리이다.

  1-1 https://mapstruct.org/documentation/stable/reference/html/ 문서를 참고 한다.

 

2. 주된 목표는 하나의 클래스를 다른 클래스로 변환해주는 기능을 Annotation으로 지원 한다.

 

3. 공식 홈페이지는 https://mapstruct.org 이고 아래와 같이 Maven에 설정하면 된다.

  3-1 1.3.1 버전기준이다.

  3-2 두개의 artifacts가 필요하다.

    3-2-1 mapstruct: @Mapping 같은 annotation을 정의한다.

    3-2-2 mapstruct-processor: 코드를 생성해주는 Annotation 처리 프로세스를 수생한다.

 

 

...
<properties>
    <org.mapstruct.version>1.3.1.Final</org.mapstruct.version>
</properties>
...
<dependencies>
    <dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct</artifactId>
        <version>${org.mapstruct.version}</version>
    </dependency>
</dependencies>
...
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.5.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <annotationProcessorPaths>
                    <path>
                        <groupId>org.mapstruct</groupId>
                        <artifactId>mapstruct-processor</artifactId>
                        <version>${org.mapstruct.version}</version>
                    </path>
                </annotationProcessorPaths>
            </configuration>
        </plugin>
    </plugins>
</build>

 

  3-3 실제 프로젝트에서 사용할 때는 lombok과 같이 사용하므로 아래처럼 정의하면 된다.

 

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.3.3.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
  </parent>
  <groupId>pe.pilseong</groupId>
  <artifactId>restdemo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>restdemo</name>
  <description>Demo project for Spring Boot</description>

  <properties>
    <java.version>11</java.version>
    <org.mapstruct.version>1.3.1.Final</org.mapstruct.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-devtools</artifactId>
      <scope>runtime</scope>
      <optional>true</optional>
    </dependency>

    <dependency>
      <groupId>org.mapstruct</groupId>
      <artifactId>mapstruct</artifactId>
      <version>${org.mapstruct.version}</version>
    </dependency>

    <dependency>
      <groupId>com.h2database</groupId>
      <artifactId>h2</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
      <exclusions>
        <exclusion>
          <groupId>org.junit.vintage</groupId>
          <artifactId>junit-vintage-engine</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.5.1</version>
        <configuration>
          <source>11</source>
          <target>11</target>
          <annotationProcessorPaths>
            <path>
              <groupId>org.mapstruct</groupId>
              <artifactId>mapstruct-processor</artifactId>
              <version>${org.mapstruct.version}</version>
            </path>
            <path>
              <groupId>org.projectlombok</groupId>
              <artifactId>lombok</artifactId>
              <version>${lombok.version}</version>
            </path>
          </annotationProcessorPaths>
          <compilerArgs>
            <compilerArg>
                -Amapstruct.defaultComponentModel=spring
            </compilerArg>
          </compilerArgs>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

 

4. 코드 생성 예제

  4-1 아래처럼 Category Domain 클래스를 아래의 DTO로 매핑한다.

 

package pe.pilseong.restdemo.domain;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

import lombok.Data;

@Data
@Entity
public class Category {

  @Id
  @GeneratedValue(strategy =GenerationType.IDENTITY)
  private Long id;

  private String name;

  private String category_url;
}



package pe.pilseong.restdemo.api.v1.model;

import lombok.Data;

@Data
public class CategoryDTO {
  private Long id;

  private String name;
}

 

  4-2 아래처럼 

    4-2-1 매핑 설정은 interface로 하고 컴파일시에 구현 클래스가 자동생성된다.

 

package pe.pilseong.restdemo.api.v1.mapper;

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

import pe.pilseong.restdemo.api.v1.model.CategoryDTO;
import pe.pilseong.restdemo.domain.Category;

@Mapper
public interface CategoryMapper {
  CategoryMapper INSTANCE = Mappers.getMapper(CategoryMapper.class);

  CategoryDTO categoryToCateotryDTO(Category category);
  
  Category categoryDTOToCategory(CategoryDTO categoryDTO);
}

 

    4-2-2 자동생성 클래스

      4-2-2-1 결과 소스 파일에 @Component가 붙은 것은

      4-2-2-2 pom에 compilerArg 옵션 -Amapstruct.defaultComponentModel=spring 이 지정되었기 때문이다.

      4-2-2-3 즉, 자동으로 스프링에 의해 컴포넌트가 생성되고 autowired 된다.

 

package pe.pilseong.restdemo.api.v1.mapper;

import javax.annotation.processing.Generated;
import org.springframework.stereotype.Component;
import pe.pilseong.restdemo.api.v1.model.CategoryDTO;
import pe.pilseong.restdemo.domain.Category;

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2020-09-02T19:58:59+0900",
    comments = "version: 1.3.1.Final, compiler: javac, environment: Java 11.0.2 (Oracle Corporation)"
)
@Component
public class CategoryMapperImpl implements CategoryMapper {

    @Override
    public CategoryDTO categoryToCateotryDTO(Category category) {
        if ( category == null ) {
            return null;
        }

        CategoryDTO categoryDTO = new CategoryDTO();

        categoryDTO.setId( category.getId() );
        categoryDTO.setName( category.getName() );

        return categoryDTO;
    }

    @Override
    public Category categoryDTOToCategory(CategoryDTO categoryDTO) {
        if ( categoryDTO == null ) {
            return null;
        }

        Category category = new Category();

        category.setId( categoryDTO.getId() );
        category.setName( categoryDTO.getName() );

        return category;
    }
}

 

5. 테스트 하기

 

package pe.pilseong.restdemo.api.v1.mapper;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import pe.pilseong.restdemo.api.v1.model.CategoryDTO;
import pe.pilseong.restdemo.domain.Category;

public class CategoryMapperTest {

  @BeforeEach
  public void setup() {

  }

  @Test
  public void categoryToCategoryDTO() {
    Category category = new Category();
    category.setId(1L);
    category.setName("Ebook");

    CategoryDTO categoryDto = CategoryMapper.INSTANCE.categoryToCateotryDTO(category);

    assertEquals(1L, categoryDto.getId());
    assertEquals("Ebook", categoryDto.getName());
  }
}