Spring Boot 2.0, Maven 기반 프로젝트에 Java, Kotlin 동시에 사용하기

개요

• Maven 기반의 Java, Spring Boot 2(또는 이 것을 한 번 다 감싼 JHipster) 프로젝트에서 Kotlin을 동시에 사용할 수 있는 방법을 정리하였다. 모든 항목을 전부 이해한 것은 아니며, JHipster와 KHipster의 프로젝트 자동 생성 결과물을 비교하여 추출하여 정상 작동을 확인하였다.

pom.xml

• 프로젝트 루트의 /pom.xml 파일에 각 부분에 아래 내용을 추가해야 한다.

<project>

    <properties>
        <!-- 아래에 추가 -->
        <kotlin.version>1.6.10</kotlin.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!-- 아래에 추가 -->
            <dependency>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-stdlib</artifactId>
                <version>${kotlin.version}</version>
            </dependency>
            <dependency>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-stdlib-jdk8</artifactId>
                <version>${kotlin.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <!-- 아래에 추가 -->
        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-debug</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-reactor</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlinx</groupId>
            <artifactId>kotlinx-coroutines-slf4j</artifactId>
        </dependency>
        <dependency>
            <groupId>io.projectreactor.kotlin</groupId>
            <artifactId>reactor-kotlin-extensions</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-json-org</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-jdk8</artifactId>
            <version>${kotlin.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-reflect</artifactId>
            <version>${kotlin.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-test-junit</artifactId>
            <version>${kotlin.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.nhaarman.mockitokotlin2</groupId>
            <artifactId>mockito-kotlin</artifactId>
            <version>2.2.0</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <!-- 아래에 추가 -->
        <sourceDirectory>src/main/java</sourceDirectory>
        <testSourceDirectory>src/test/java</testSourceDirectory>
        <plugins>
            <!-- 아래에 추가 -->
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>process-sources</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>kapt</id>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>kapt</goal>
                        </goals>
                        <configuration>
                            <sourceDirs>
                                <sourceDir>${project.basedir}/src/main/java</sourceDir>
                            </sourceDirs>
                            <annotationProcessorPaths>
                                <annotationProcessorPath>
                                    <groupId>com.querydsl</groupId>
                                    <artifactId>querydsl-apt</artifactId>
                                    <version>${querydsl.version}</version>
                                    <classifier>jpa</classifier>
                                </annotationProcessorPath>
                                <annotationProcessorPath>
                                    <groupId>org.mapstruct</groupId>
                                    <artifactId>mapstruct-processor</artifactId>
                                    <version>${mapstruct.version}</version>
                                </annotationProcessorPath>
                                <annotationProcessorPath>
                                    <groupId>org.glassfish.jaxb</groupId>
                                    <artifactId>jaxb-runtime</artifactId>
                                    <version>${jaxb-runtime.version}</version>
                                </annotationProcessorPath>
                            </annotationProcessorPaths>
                        </configuration>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>test-compile</goal>
                        </goals>
                        <configuration>
                            <sourceDirs>
                                <sourceDir>${project.basedir}/src/test/java</sourceDir>
                                <sourceDir>${project.basedir}/target/generated-sources/kapt/test</sourceDir>
                            </sourceDirs>
                        </configuration>
                    </execution>
                </executions>
                <configuration>
                    <jvmTarget>${java.version}</jvmTarget>
                    <javaParameters>true</javaParameters>
                    <args>
                        <arg>-Xjvm-default=enable</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                        <plugin>jpa</plugin>
                        <plugin>all-open</plugin>
                        <plugin>kotlinx-serialization</plugin>
                    </compilerPlugins>
                    <pluginOptions>
                        <option>all-open:annotation=javax.persistence.Entity</option>
                        <option>all-open:annotation=javax.persistence.MappedSuperclass</option>
                        <option>all-open:annotation=javax.persistence.Embeddable</option>
                    </pluginOptions>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-noarg</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-serialization</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>${maven-compiler-plugin.version}</version>
                    <configuration>
                        <source>${java.version}</source>
                        <target>${java.version}</target>
                        <annotationProcessorPaths>
                            <path>
                                <groupId>org.springframework.boot</groupId>
                                <artifactId>spring-boot-configuration-processor</artifactId>
                                <version>${spring-boot.version}</version>
                            </path>
                            <path>
                                <groupId>org.mapstruct</groupId>
                                <artifactId>mapstruct-processor</artifactId>
                                <version>${mapstruct.version}</version>
                            </path>
                            <path>
                                <groupId>org.glassfish.jaxb</groupId>
                                <artifactId>jaxb-runtime</artifactId>
                                <version>${jaxb-runtime.version}</version>
                            </path>
                        </annotationProcessorPaths>
                    </configuration>
                    <executions>
                        <execution>
                            <id>default-compile</id>
                            <phase>none</phase>
                        </execution>
                        <execution>
                            <id>default-testCompile</id>
                            <phase>none</phase>
                        </execution>
                        <execution>
                            <id>java-compile</id>
                            <phase>compile</phase>
                            <goals>
                                <goal>compile</goal>
                            </goals>
                        </execution>
                        <execution>
                            <id>java-test-compile</id>
                            <phase>test-compile</phase>
                            <goals>
                                <goal>testCompile</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
        </plugins>
    </build>

</project>

트러블슈팅: hibernate-jpamodelgen 빌드 오류 발생

• 프로젝트 빌드시 아래 오류가 발생했다.

org.apache.maven.plugin.compiler.CompilationFailureException: Compilation failure

• hibernate-jpamodelgen 패키지와의 충돌이 원인인데 아래 코드를 제거해야 한다. [관련 링크] (JDK 6 이상부터는 <project><dependencies> 내에 선언되어 있기만 해도 빌드 시점에 자동으로 크라이테리아를 위한 _ 클래스를 생성하기 때문에 제거해도 전혀 문제가 되지 않는다. [관련 링크])

<path>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-jpamodelgen</artifactId>
    <version>${hibernate.version}</version>
</path>

참고 글

• JPA Static Metamodel Generator