Repository

Repository

• 의존성을 가져올 공개 호스팅 온라인 서비스
• Maven Central, Google Maven을 지원하고 있음
• build script에 repository 명시 필요

resolve dependency

• gradle이 build script에 명시된 의존성을 확인하고 repository로부터 fetch하는 의존성 해결프로세스

repository 선언

gradle은 resolve 시 명시한 순서대로 의존성을 repository에서 찾음

repositories {
    mavenCentral()
    google()
    maven {
        url = uri("https://custom-repo.com")
    }
}

Dependency Metadata

Dependency : build script에 명시한 project build 시 필요한 의존성(artifact)들

repository format

• Maven(Maven Central, Google Maven)
• Ivy
• flat directory(local storage)

.pom file that is describes project

maven repository에 publish되는 artifact는 .pom 파일에 프로젝트에 대한 정보를 설명해놓음

gradle은 해당 정보를 통해 의존성을 가져옴(dependency coordinate)

또한 해당 파일에 transitive 의존성이 명시되어 있는데 gradle은 전체 의존성을 파악하여 모두 가져옴

• group id
• name(artifact id)
• version

transitive dependency

• artifact가 의존하는 다른 artifact

특정 의존성 모듈 제외 명시 방법

transitive 의존성을 제외하는 경우 해당 의존성을 필요로 하는 의존성마다 exclude를 명시 해줘야 됨

// transitive dependency 제외
implementation("group:artifact:version") {
    exclude(group = "group", module = "module")
}

Classpath, Production classpath

프로젝트를 빌드하는 동안 여러 단계를 거침

컴파일 -> 테스트 -> 실행

자바의 classpath는 애플리케이션을 컴파일하거나 실행할 때 jvm에게 전달되는 파일 리스트임

Compile phase requires compile classpath and run phase requires runtime classpath

Gradle gives us fine-grained control of classpath using dependency configurations

compile classpath

• Classpath is used to compile code
• A list of all the libraries referenced by the code to be compiled
• Java eliminates the need to load unnecessary libraries

runtime classpath

• Classpath is used to run the compiled code
• which may or not be the same as the compile classpath
• Application(artifact) eliminates the need to include unnecessary libraries

production classpath

• compile classpath + runtime classpath
• Classspaths required to compile and run a java application
• also is not include test code

Production classpath dependency configuration

implementation("group:artifact:version")

implementation(group = "group", name = "artifact", version = "version")

dependency configuration

• Used to specify about dependency where it will add to the certain classpath

Note

• A dependency configuration can inherit from another, which means it inherits all the dependencies declared on the parent
• There are actually two types of dependency configurations
  • unresolvable : dependency configuration are used for declaring dependencies only, all that we write dependency in build script are this type
    • implementation, compileOnly, runtimeOnly or etc
  • resolvable : dependency configuration are used by Gradle to calculate things like the compile classpath, but you can’t declare dependencies against them
    • compileClasspath, runtimeClasspath

Each resolvable dependency configuration has combination of unresolvable dependency configurations

• compileClasspath is a combination of the implementation and compileOnly dependencies
• runtimeClasspath is a combination of the implementation and runtimeOnly dependencies

production classpath dependency configuration

• compileOnly
  • Use when the dependency is only needed on the compile classpath
  • Dependency has already provided in the deployed environment but need to compile the code
• implementation
  • When used to required at compileClasspath and runtimeClasspath
  • Use when your application’s code interacts directly with code from a dependency
• runtimeOnly
  • Use when the dependency is only needed on the runtime classpath
  • When your application needs to connect to a database. Most case from a code perspective it interacts with the database-agnostic JPA or JDBC SPI.
  • Only at runtime do you include the library for the specific database implementation you’re using
• annotationProcessor
  • When java code is compiled it has the additional feature whereby additional source file can be generated by annotation processor
  • The java compiler accepts a processor path on the command line, which is a list of all the annotation processor libraries
  • The annotationProcessor dependency configuration controls this processor path

 annotationProcessor("org.projectlombok:lombok:1.18.32")

dependency configuration that java plugin uses

• CompileJava task of java plugin uses compileClasspath configuration to generate the classpath
• and java plugin itself doesn’t hava any task that use runtimeClasspath

Test classpath dependency configuration

Similar to production classpath, tests have their own testCompileClassPath, testRuntimeClasspath resolvable dependency configurations

They also have their own testCompileOnly, testImplementation and testRuntimeOnly unresolvable dependency configurations which you can declare against

test dependency configurations extend other

• Test dependency configuration extends the production ones
  • TestImplementation extends the implementation configuration
  • TestRuntimeOnly extends the runtimeOnly configuration
• As a result, declared dependency in production classpath can be used in tests

compileTestJava, test task of java plugin

• compileTestJava task resolves testCompileClasspath dependency configuration to generate the test compile classpath, which is used to compile test code
• test task resolves testRuntimeClasspath dependency configuration to generate the test runtime classpath, which is used to run the tests