gradle 创建 jar 不适用于“实现”依赖项

Question

I am new to gradle and trying to generate a jar from a simple hello world java grpc and below is my build.gradle

plugins {
    id 'application'
    id 'com.google.protobuf' version '0.8.12'
    id 'idea'
    id 'java'
}

version '1.0'

sourceCompatibility = 1.8

repositories {
    mavenLocal()
    maven { // The google mirror is less flaky than mavenCentral()
        url "https://maven-central.storage-download.googleapis.com/repos/central/data/" }
    mavenCentral()
}

dependencies {
    implementation 'io.grpc:grpc-netty-shaded:1.29.0'
    implementation 'io.grpc:grpc-protobuf:1.29.0'
    implementation 'io.grpc:grpc-stub:1.29.0'
    testCompile group: 'junit', name: 'junit', version: '4.12'
}


protobuf {
    protoc {
        artifact = "com.google.protobuf:protoc:3.11.0"
    }
    plugins {
        grpc {
            artifact = 'io.grpc:protoc-gen-grpc-java:1.29.0'
        }
    }
    generateProtoTasks {
        all()*.plugins {
            grpc {}
        }
    }
}

sourceSets {
    main {
        java {
            srcDirs 'build/generated/source/proto/main/grpc'
            srcDirs 'build/generated/source/proto/main/java'
        }
    }
}

startScripts.enabled = false

task helloWorldServer(type: CreateStartScripts) {
    mainClassName = 'com.javagrpc.HelloWorldServer'
    applicationName = 'hello-world-server'
    outputDir = new File(project.buildDir, 'tmp')
    classpath = startScripts.classpath
}

applicationDistribution.into('bin') {
    from(helloWorldServer)
    fileMode = 0755
}

distZip.shouldRunAfter(build)

jar {
    manifest {
        attributes 'Main-Class': 'com.examples.javagrpc.HelloWorldServer',
        'Class-Path': configurations.runtime.files.collect { "lib/$it.name" }.join(' ')
    }

    from {
        configurations.compile.collect { it.isDirectory() ? it : zipTree(it) }
    }
    exclude 'META-INF/*.RSA', 'META-INF/*.SF','META-INF/*.DSA'
}

I started running into issue when I run the task 'gradle jar' it builds a jar inside build/libs when I run the jar its fails with java.lang.NoClassDefFoundError: io/grpc/BindableService I unpacked the jar and didn't find the grpc dependencies inside it. I tried running the generated files directly

./build/install/java-grpc/bin/hello-world-server

and it works as expected. To resolve the jar issue, I decided to change the above dependencies from implementation to api as below.

dependencies {
    api 'io.grpc:grpc-netty-shaded:1.29.0'
    api 'io.grpc:grpc-protobuf:1.29.0'
    api 'io.grpc:grpc-stub:1.29.0'
    testCompile group: 'junit', name: 'junit', version: '4.12'
}

Now everything works as expected the dependencies are inside the jar and I can run the jar. But I am not sure whether I shall be using api or not in my dependencies since the official example does not uses it? Maybe I am not correctly generating the jar and it can be generated just with dependencies implementation any help or pointers is highly appreciated.

Answer 1

The problem is that the jar task modification you use does not take advantage of the new dependency configurations.

Instead of collection the dependencies from compile , you really want to collect the dependencies from runtimeClasspath in your uber JAR. After all, in order to run, it will need all dependencies declared in implementation but runtimeOnly as well. See the documentation to better understand the relationship between these configurations.

jar {
    ...
    from {
        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
    }
    ...
}