Android 构建篇(2)：以 Android 工程为例讲述 Gradle

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本文以 Android 工程为例讲述 Gradle
Android Project

一、以 Android 工程为例

1. gradle-wrapper.properties of project

$rootProject.projectDir/gradle-wrapper.properties
上文提过，此文件用于配置构建该 project 的 Gradle 版本等

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distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-all.zip

2. gradle.properties of project

$rootProject.projectDir/gradle.properties
此文件用于配置全局构建环境等

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# Project-wide Gradle settings.

# IDE (e.g. Android Studio) users:
# Gradle settings configured through the IDE *will override*
# any settings specified in this file.

# For more details on how to configure your build environment visit
# http://www.gradle.org/docs/current/userguide/build_environment.html

# Specifies the JVM arguments used for the daemon process.
# The setting is particularly useful for tweaking memory settings.
org.gradle.jvmargs=-Xmx1536m

# When configured, Gradle will run in incubating parallel mode.
# This option should only be used with decoupled projects. More details, visit
# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
# org.gradle.parallel=true

以下设置条件允许可提高构建速度
(1) org.gradle.jvmargs=-Xmx1536m
JVM 最大允许分配的堆内存，条件允许的话，值越大，构建速度越快
(2) org.gradle.parallel=true
并行构建，条件允许可提高构建速度
(3) org.gradle.daemon=true
使用守护进程，条件允许可提高构建速度
Gradle 守护进程是一个后台进程, 运行着繁重的构建, 并在等待下一次构建的时保持自身存在，准备好下一次构建的数据和代码，存入内存中，提高后续构建的性能
注：开发机器上建议开启 Gradle 守护进程，但在持续继承环境下不推荐，参考 When should I not use the Gradle Daemon?)

3. local.properties of project

$rootProject.projectDir/local.properties
配置 Android SDK、NDK 路径

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sdk.dir=/Users/yutinglin/Documents/sdk/android

4. settings.gradle of project

$rootProject.projectDir/settings.gradle
对应一个 Settings 对象，包括 void include(String[] projectPaths)) 方法
用于指定哪些 module 参与构建

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include ':app'

5. build.gradle of project

$rootProject.projectDir/build.gradle
对应一个Project对象

5.1 Project 具备 buildscript 属性

包括自身及 subprojects

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# 配置 Android Gradle Plugin
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        # 指定 Android Gradle Plugin 版本号
        classpath 'com.android.tools.build:gradle:2.2.2'

        // NOTE: Do not place your application config here; they belong
        // in the individual module build.gradle files
    }
}

5.2 Project 具备 allprojects 属性

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# 配置 top-level project 及 modules
allprojects {
    repositories {
        jcenter()
    }
}

5.3 Project 具备 task(name)) 方法

用于创建一个 Task 并添加到该 Project 对象

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

6. build.gradle of module

$projectDir/build.gradle 对应一个 Project 对象

6.1 Project 具备 void apply(Map options)) 方法

引用 void apply(Map options))

The following options are available:
from: A script to apply.
plugin: The id or implementation class of the plugin to apply.
to: The target delegate object or objects. The default is this plugin aware object. Use this to configure objects other than this object.

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apply plugin: 'com.android.application'

引用 Gradle Guides - Building Android apps

applying the Android plugin adds a wide variety of tasks, which are configured by the android block shown next.

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android {
    # Android SDK API Level
    compileSdkVersion 25
    # Android SDK Build-tools
    buildToolsVersion "25.0.2"
    # 所有 Build Variants 共享的配置
    defaultConfig {
        # package name
        applicationId "org.gradle.helloworldgradle"
        minSdkVersion 15
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner
            "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            # 混淆
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),
                'proguard-rules.pro'
        }
    }
}

6.2 Project 具备 dependencies 属性

配置依赖

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dependencies {
    # 依赖 $projectDir/libs/*.jar
    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-v7:25.1.1'
    testCompile 'junit:junit:4.12'
}

二、Android 构建流程

引用 构建流程
Android 构建流程

三、参考

Gradle Guides - Building Android apps
When should I not use the Gradle Daemon?
构建流程