Building Android Apps with Gradle

See some of the features of the Android plugin for Gradle in action.

Transcript

1. Building Android Apps
   with Gradle
   

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2. Gradle
   • Build automation tool, builds upon Maven and
   Ant
   • Uses build.gradle files for configuration
   !
   PROTIP
   • Use the gradle wrapper
   http://www.gradle.org/
   

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3. Gradle android plugin
   Build with `./gradlew clean assemble`
   !
   Android Tasks
   • assemble
   • clean
   • connectedCheck
   • deviceCheck
   • check
   • build
   !
   ./gradlew tasks --all
   http://tools.android.com/
   tech-docs/new-build-system/
   user-guide
   

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4. Basic App Structure
   Project
   ├── app
   │ ├── build.gradle
   │ ├── keystore
   │ ├── libs
   │ │ └── *.jar
   │ └── src
   └── build.gradle
   

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5. Top level build file
   Project
   ├── app
   │ ├── build.gradle
   │ ├── keystore
   │ ├── libs
   │ │ └── *.jar
   │ └── src
   └── build.gradle
   Add configuration
   options common to all
   sub-projects/modules.
   !
   task wrapper(type: Wrapper) {
   gradleVersion = '1.8'
   }
   

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6. Module build file
   Main application build
   file. It would contain
   information such as
   dependencies, plugins,
   etc.
   With the Android plugin,
   you can define
   additional properties for
   your application, such
   as package name,
   version code, etc.
   Project
   ├── app
   │ ├── build.gradle
   │ ├── keystore
   │ ├── libs
   │ │ └── *.jar
   │ └── src
   └── build.gradle
   

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7. Sample build.gradle for
   an Android app
   https://github.com/f2prateek/android-device-frame-
   generator/blob/master/app/build.gradle
   

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8. Basic App Structure
   My build.gradle is
   configured to pick up all jars
   in this folder. Use this for
   dependencies not available
   via published repositories.
   !
   compile fileTree(dir: 'libs', include: '*.jar')
   .
   ├── app
   │ ├── build.gradle
   │ ├── keystore
   │ ├── libs
   │ │ └── *.jar
   │ └── src
   └── build.gradle
   

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9. Sources
   Project
   ├── app
   │ ├── build.gradle
   │ ├── keystore
   │ ├── libs
   │ │ └── *.jar
   │ └── src
   └── build.gradle
   

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10. Sources
    │ └── src
    │ ├── debug
    │ │ └── AndroidManifest.xml
    │ ├── instrumentTest
    │ │ ├── AndroidManifest.xml
    │ │ └── java
    │ ├── main
    │ │ ├── AndroidManifest.xml
    │ │ ├── java
    │ │ └── res
    │ └── release
    │ ├── AndroidManifest.xml
    │ └── res
    │ └── values
    │ └── analytics.xml
    

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11. Main Source Set
    │ └── src
    │ ├── debug
    │ │ └── AndroidManifest.xml
    │ ├── instrumentTest
    │ │ ├── AndroidManifest.xml
    │ │ └── java
    │ ├── main
    │ │ ├── AndroidManifest.xml
    │ │ ├── java
    │ │ └── res
    │ └── release
    │ ├── AndroidManifest.xml
    │ └── res
    │ └── values
    │ └── analytics.xml
    The default source set.
    Stick to this if you want
    no build customization.
    

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12. Instrument Tests Source Sets
    │ └── src
    │ ├── debug
    │ │ └── AndroidManifest.xml
    │ ├── instrumentTest
    │ │ ├── AndroidManifest.xml
    │ │ └── java
    │ ├── main
    │ │ ├── AndroidManifest.xml
    │ │ ├── java
    │ │ └── res
    │ └── release
    │ ├── AndroidManifest.xml
    │ └── res
    │ └── values
    │ └── analytics.xml
    

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13. Build Types
    │ └── src
    │ ├── debug
    │ │ └── AndroidManifest.xml
    │ ├── instrumentTest
    │ │ ├── AndroidManifest.xml
    │ │ └── java
    │ ├── main
    │ │ ├── AndroidManifest.xml
    │ │ ├── java
    │ │ └── res
    │ └── release
    │ ├── AndroidManifest.xml
    │ └── res
    │ └── values
    │ └── analytics.xml
    The Android plugin
    gives you release and
    debug configurations
    for free. Simply create
    a source folder for
    each configuration
    and get started with
    basic build
    customization.
    

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14. Build Types
    Some added tasks:
    • assembleDebug
    • assembleRelease
    !
    ./gradlew assembleRelease
    OR
    ./gradlew aR
    Each configuration
    creates some
    appropriate
    corresponding tasks.
    

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15. Android Configuration
    defaultConfig {
    
    minSdkVersion 14
    
    targetSdkVersion 19
    
    packageName "com.f2prateek.dfg"
    
    versionCode versionMajor * 10000 + versionMinor * 1000 + versionPatch * 100 + versionBuild
    
    versionName "${versionMajor}.${versionMinor}.${versionPatch}"
    
    buildConfig """\
    
    public static final int VERSION_MAJOR = ${versionMajor}.;
    
    """
    
    }
    def versionMajor = 2
    
    def versionMinor = 0
    
    def versionPatch = 0
    
    def versionBuild = 1
    

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16. Android Configuration
    This sample :
    • Defines minSdkVersion and maxSdkVersion
    • Defines package name
    • Defines version code and version name
    • Adds version name to BuildConfig (access it with
    BuildConfig.VERSION_MAJOR, no need for a
    Context!). Next version of the build tools will have
    more information out of the box, such as package
    name, version name, version code, etc.
    

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17. Customizing Builds
    
    debug {
    
    packageNameSuffix ".debug"
    
    versionNameSuffix "-debug"
    
    }
    
    release {
    
    signingConfig signingConfigs.release
    
    }
    

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18. Customizing Builds
    This sample :
    • Adds a suffix to the package name for debug
    build types
    • Adds a suffix to the version name for debug
    build types
    • Configures release build types to use a
    signing configuration that is shown in the next
    slide
    

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19. Customizing Builds : Merging
    • All build types share code from the main
    source set
    • The manifest is merged into the app manifest
    • The code acts as just another source folder
    • The resources are overlayed over the main
    resources, replacing existing values
    

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20. Customizing Builds : Uses
    • Permissions in debug mode only, but not in
    release mode
    • Custom implementation for debugging
    • Different resources for debug mode (for
    instance when a resource value is tied to the
    signing certificate)
    

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21. Custom Build Types
    beta.initWith(buildTypes.release)
    
    beta {
    
    versionNameSuffix "-beta"
    
    }
    
    sourceSets.beta.setRoot('src/release')
    This creates a custom build
    type named ‘beta’, initializing
    it from the properties of the
    release build type.
    By default, it would have it’s
    source set under ‘src/beta’.
    Here I manually set the
    source set to be under ‘src/
    release’. The only difference
    between the two versions in
    my case is that beta has a
    suffix in it’s version name.
    

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22. Signing packages
    signingConfigs {
    
    release {
    
    storeFile file("keystore")
    
    storePassword "notYourRealPassword"
    
    keyAlias "keystore"
    
    keyPassword "notYourRealPassword"
    
    }
    
    }
    task askForPasswords << {
    
    def storePassword = new String(System.console().readLine("\n\$ Enter keystore password: "))
    
    def keyPassword = new String(System.console().readLine("\n\$ Enter key alias password: "))
    
    android.signingConfigs.release.storePassword = storePassword
    
    android.signingConfigs.release.keyPassword = keyPassword
    
    }
    
    !
    tasks.whenTaskAdded { theTask ->
    
    if (theTask.name.equals("validateReleaseSigning")) {
    
    theTask.dependsOn "askForPasswords"
    
    }
    
    }
    

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23. Signing packages
    This uses a file ‘keystore’ with an
    alias ‘keystore’. It asks for a
    password for both via the
    command line. Alternatively, you
    can make it pick up system
    properties, or pick them up in a
    file like signing.properties
    

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24. Renaming the .apk file
    applicationVariants.all { variant ->
    
    apk = variant.packageApplication.outputFile;
    
    newName = apk.name.replace(".apk", "-v${defaultConfig.versionName}-${versionBuild}.apk");
    
    newName = newName.replace("app", "${defaultConfig.packageName}");
    
    variant.packageApplication.outputFile = new File(apk.parentFile, newName);
    
    if (variant.zipAlign) {
    
    variant.zipAlign.outputFile = new File(apk.parentFile, newName.replace("-unaligned", ""));
    
    }
    
    }
    

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25. Renaming the .apk file
    Produces the following apk’s
    • com.f2prateek.dfg-beta-unaligned-v2.0.0-1.apk
    
    • com.f2prateek.dfg-beta-v2.0.0-1.apk
    
    • com.f2prateek.dfg-debug-unaligned-v2.0.0-1.apk
    
    • com.f2prateek.dfg-release-unaligned-v2.0.0-1.apk
    
    • com.f2prateek.dfg-release-v2.0.0-1.apk
    

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26. Checkstyle (thank Jake Wharton!)
    apply plugin: 'checkstyle'
    
    !
    checkstyle {
    
    configFile project.file('../checkstyle.xml')
    
    showViolations true
    
    }
    
    !
    android.applicationVariants.all { variant ->
    
    def name = variant.buildType.name
    
    def checkstyle = project.tasks.create "checkstyle${name.capitalize()}", Checkstyle
    
    checkstyle.dependsOn variant.javaCompile
    
    checkstyle.source variant.javaCompile.source
    
    checkstyle.classpath = project.fileTree(variant.javaCompile.destinationDir)
    
    checkstyle.exclude('**/BuildConfig.java')
    
    checkstyle.exclude('**/R.java')
    
    project.tasks.getByName("check").dependsOn checkstyle
    
    }
    

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27. Checkstyle for library projects
    apply plugin: 'checkstyle'
    
    !
    checkstyle {
    
    configFile project.file('../checkstyle.xml')
    
    showViolations true
    
    }
    
    !
    android.libraryVariants.all { variant ->
    
    def name = variant.buildType.name
    
    def checkstyle = project.tasks.create "checkstyle${name.capitalize()}", Checkstyle
    
    checkstyle.dependsOn variant.javaCompile
    
    checkstyle.source variant.javaCompile.source
    
    checkstyle.classpath = project.fileTree(variant.javaCompile.destinationDir)
    
    checkstyle.exclude('**/BuildConfig.java')
    
    checkstyle.exclude('**/R.java')
    
    project.tasks.getByName("check").dependsOn checkstyle
    
    }
    

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28. Sample of Manifest in
    release, debug and
    main
    https://github.com/f2prateek/
    android-device-frame-generator
    

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