问题

I have a library project with a module that is just for library classes and views. I've been searching over the internet how to distribute it in jCenter to use as a gradle dependency but nothing works.

While this isn't done yet, how can I use this module in others projects?

PS: I use Android Studio on Windows 10.

回答1:

Many of the tutorials and directions online are out of date or are very hard to follow. I just learned how to do this myself, so I am adding what will hopefully be a quick solution for you. It includes the following points

Start with your Android library
Set up a Bintray account
Edit your project's gradle files
Upload your project to Bintray
Link it to jCenter

The library you want to share

By now you probably already have a library set up. For the sake of this example I made a new project with one demo-app application module and one my-library library module in Android Studio.

Here is what it looks like using both the Project and Android views:

Set up a Bintray account

Bintray hosts the jCenter repositories. Go to Bintray and set up a free account.

After you sign in click Add New Repository

Name the repository maven. (You can call it something else, though, if you want to group several library projects together. If you do you will also need to change the bintrayRepo name in the gradle file below.)

Chose Maven as the repository type.

You can add a description if you want. Then click Create. That's all we need to do in Bintray for now.

Edit the gradle files

I'm going to make this as cut-and-paste as possible, but don't forget to edit the necessary parts. You don't need to do anything with the demo app module's build.gradle file, only the gradle files for the project and the library.

Project build.gradle

Add the Bintray and Mavin plugins to your project build.gradle file. Here is my whole file:

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.2'

        // Add these lines (update them to whatever the newest version is)
        classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.3'
        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.5'
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

The newest version for Bintray is here and Maven is here.

Library build.gradle

Edit everything you need to in the ext block below.

apply plugin: 'com.android.library'

// change all of these as necessary
ext {
    bintrayRepo = 'maven'  // this is the same as whatever you called your repository in Bintray
    bintrayName = 'my-library' // your bintray package name. I am calling it the same as my library name.

    publishedGroupId = 'com.example'
    libraryName = 'my-library'
    artifact = 'my-library' // I'm calling it the same as my library name

    libraryDescription = 'An example library to make your programming life easy'

    siteUrl = 'https://github.com/example/my-library'
    gitUrl = 'https://github.com/example/my-library.git'

    libraryVersion = '1.0.0'

    developerId = 'myID' // Maven plugin uses this. I don't know if it needs to be anything special.
    developerName = 'My Name'
    developerEmail = 'myemail@example.com'

    licenseName = 'The MIT License (MIT)'
    licenseUrl = 'https://opensource.org/licenses/MIT'
    allLicenses = ["MIT"]
}

// This next section is your normal gradle settings
// There is nothing special that you need to change here
// related to Bintray. Keep scrolling down.

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"

    defaultConfig {
        minSdkVersion 9
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.3.1'
    testCompile 'junit:junit:4.12'
}

// Maven section
// You shouldn't need to change anything. It just uses the
// values you set above.

apply plugin: 'com.github.dcendents.android-maven'

group = publishedGroupId // Maven Group ID for the artifact

install {
    repositories.mavenInstaller {
        // This generates POM.xml with proper parameters
        pom {
            project {
                packaging 'aar'
                groupId publishedGroupId
                artifactId artifact

                // Add your description here
                name libraryName
                description libraryDescription
                url siteUrl

                // Set your license
                licenses {
                    license {
                        name licenseName
                        url licenseUrl
                    }
                }
                developers {
                    developer {
                        id developerId
                        name developerName
                        email developerEmail
                    }
                }
                scm {
                    connection gitUrl
                    developerConnection gitUrl
                    url siteUrl

                }
            }
        }
    }
}

// Bintray section
// As long as you add bintray.user and bintray.apikey to the local.properties
// file, you shouldn't have to change anything here. The reason you 
// don't just write them here is so that they won't be publicly visible
// in GitHub or wherever your source control is.

apply plugin: 'com.jfrog.bintray'

version = libraryVersion

if (project.hasProperty("android")) { // Android libraries
    task sourcesJar(type: Jar) {
        classifier = 'sources'
        from android.sourceSets.main.java.srcDirs
    }

    task javadoc(type: Javadoc) {
        source = android.sourceSets.main.java.srcDirs
        classpath += project.files(android.getBootClasspath().join(File.pathSeparator))
    }
} else { // Java libraries
    task sourcesJar(type: Jar, dependsOn: classes) {
        classifier = 'sources'
        from sourceSets.main.allSource
    }
}

task javadocJar(type: Jar, dependsOn: javadoc) {
    classifier = 'javadoc'
    from javadoc.destinationDir
}

artifacts {
    archives javadocJar
    archives sourcesJar
}

Properties properties = new Properties()
properties.load(project.rootProject.file('local.properties').newDataInputStream())

bintray {
    user = properties.getProperty("bintray.user")
    key = properties.getProperty("bintray.apikey")

    configurations = ['archives']
    pkg {
        repo = bintrayRepo
        name = bintrayName
        desc = libraryDescription
        websiteUrl = siteUrl
        vcsUrl = gitUrl
        licenses = allLicenses
        publish = true
        publicDownloadNumbers = true
        version {
            desc = libraryDescription
            gpg {
                // optional GPG encryption. Default is false.
                sign = false
                //passphrase = properties.getProperty("bintray.gpg.password")
            }
        }
    }
}

local.properties

The library build.gradle file above referenced some values in the local.properties file. We need to add those now. This file is located in the root of your project. It should be included in .gitignore. (If it isn't then add it.) The point of putting your username, api key, and encryption password here is so that it won't be publicly visible in version control.

## This file is automatically generated by Android Studio.
# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
#
# This file should *NOT* be checked into Version Control Systems,
# as it contains information specific to your local configuration.
#
# Location of the SDK. This is only used by Gradle.
# For customization when using a Version Control System, please read the
# header note.
sdk.dir=/home/yonghu/Android/Sdk

# Add these lines (but change the values according to your situation)
bintray.user=myusername
bintray.apikey=1f2598794a54553ba68859bb0bf4c31ff6e71746

There is a warning about not modifying this file but it seems to work well anyway. Here is how you get the values:

bintray.user: This is your Bintray username.
bintray.apikey: Go to Edit Profile in the Bintray menu and choose API Key. Copy it from here.

Upload project to Bintray

Open a terminal and go to your project's root folder. Or just use the terminal in Android Studio.

Enter the following commands

./gradlew install
./gradlew bintrayUpload

If everything is set up right it should upload your library to Bintray. If it fails then Google the solution. (I had to update my JDK the first time I tried.)

Go to your account in Bintray and you should see the library entered under your repository.

Link to jCenter

In your library in Bintray there is an Add to jCenter button.

Click it and send your request. If you are approved (which takes a day or two), then your library will be a part of jCenter and developers around the world can add your library to their projects simply by adding one line to the app build.gradle dependencies block.

dependencies {
    compile 'com.example:my-library:1.0.0'
}

Congratulations!

Notes

You may want to add PGP encryption, especially if you are linking it to Maven Central. (jCenter has replaced Maven Central as the default in Android Studio, though.) See this tutorial for help with that. But also read this from Bintray.

How to add a new version

You will eventually want to add a new version to your Bintray/jCenter library. See this answer to directions on how to do it.

distribute Android library in jCenter to use in gradle

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