向项目添加组件

在开始之前，我们建议您阅读“架构组件指南”。 该指南包含一些适用于所有Android应用程序的有用原则，并展示了如何将架构组件一起使用。

架构组件可从Google的Maven存储库获得。 要使用它们，请按照下列步骤操作：

一、添加Google Maven存储库

默认情况下，Android Studio项目未配置为访问此存储库。

要将其添加到项目中，请打开项目的build.gradle文件（而不是应用程序或模块的文件）并添加google（）存储库，如下所示：

allprojects {
    repositories {
        jcenter()
        google()
    }
}

二、声明依赖项

打开应用程序或模块的build.gradle文件，并添加所需的工件作为依赖项。 您可以添加所有依赖项，也可以选择子集。

AndroidX

Arch组件的未来版本正在作为AndroidX的一部分开发，并列在每个稳定依赖项下面。 这些alpha版本的工件名称已更改为遵循AndroidX标准。

有关AndroidX重构的更多信息，以及它如何影响类包和模块ID，请参阅AndroidX重构文档。

Kotlin

Kotlin扩展模块支持多个AndroidX依赖项，标记为// use -ktx for Kotlin，只需替换例如：

implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version" // use -ktx for Kotlin

同

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"

更多信息，包括Kotlin扩展的文档，可以在ktx文档中找到。

注意：对于基于Kotlin的应用程序，请确保使用kapt而不是annotationProcessor。 你还应该添加kotlin-kapt插件。

三、Lifecycle

生命周期的依赖关系，包括LiveData和ViewModel。

dependencies {
    def lifecycle_version = "1.1.1"

    // ViewModel and LiveData
    implementation "android.arch.lifecycle:extensions:$lifecycle_version"
    // alternatively - just ViewModel
    implementation "android.arch.lifecycle:viewmodel:$lifecycle_version" // use -ktx for Kotlin
    // alternatively - just LiveData
    implementation "android.arch.lifecycle:livedata:$lifecycle_version"
    // alternatively - Lifecycles only (no ViewModel or LiveData).
    //     Support library depends on this lightweight import
    implementation "android.arch.lifecycle:runtime:$lifecycle_version"

    annotationProcessor "android.arch.lifecycle:compiler:$lifecycle_version" // use kapt for Kotlin
    // alternately - if using Java8, use the following instead of compiler
    implementation "android.arch.lifecycle:common-java8:$lifecycle_version"

    // optional - ReactiveStreams support for LiveData
    implementation "android.arch.lifecycle:reactivestreams:$lifecycle_version"

    // optional - Test helpers for LiveData
    testImplementation "android.arch.core:core-testing:$lifecycle_version"
}

AndroidX

dependencies {
    def lifecycle_version = "2.0.0-beta01"

    // ViewModel and LiveData
    implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
    // alternatively - just ViewModel
    implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version" // use -ktx for Kotlin
    // alternatively - just LiveData
    implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"
    // alternatively - Lifecycles only (no ViewModel or LiveData). Some UI
    //     AndroidX libraries use this lightweight import for Lifecycle
    implementation "androidx.lifecycle:lifecycle-runtime:$lifecycle_version"

    annotationProcessor "androidx.lifecycle:lifecycle-compiler:$lifecycle_version" // use kapt for Kotlin
    // alternately - if using Java8, use the following instead of lifecycle-compiler
    implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"

    // optional - ReactiveStreams support for LiveData
    implementation "androidx.lifecycle:lifecycle-reactivestreams:$lifecycle_version" // use -ktx for Kotlin

    // optional - Test helpers for LiveData
    testImplementation "androidx.arch.core:core-testing:$lifecycle_version"
}

四、Room

Room的依赖关系，包括测试Room迁移和Room RxJava

dependencies {
    def room_version = "1.1.1"

    implementation "android.arch.persistence.room:runtime:$room_version"
    annotationProcessor "android.arch.persistence.room:compiler:$room_version" // use kapt for Kotlin

    // optional - RxJava support for Room
    implementation "android.arch.persistence.room:rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "android.arch.persistence.room:guava:$room_version"

    // Test helpers
    testImplementation "android.arch.persistence.room:testing:$room_version"
}

AndroidX

dependencies {
    def room_version = "2.0.0-beta01"

    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version" // use kapt for Kotlin

    // optional - RxJava support for Room
    implementation "androidx.room:room-rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "androidx.room:room-guava:$room_version"

    // Test helpers
    testImplementation "androidx.room:room-testing:$room_version"
}

五、Paging

Paging的依赖性

dependencies {
    def paging_version = "1.0.0"

    implementation "android.arch.paging:runtime:$paging_version"

    // alternatively - without Android dependencies for testing
    testImplementation "android.arch.paging:common:$paging_version"

    // optional - RxJava support, currently in release candidate
    implementation "android.arch.paging:rxjava2:1.0.0-rc1"
}

AndroidX

dependencies {
    def paging_version = "2.0.0-beta01"

    implementation "androidx.paging:paging-runtime:$paging_version"

    // alternatively - without Android dependencies for testing
    testImplementation "androidx.paging:paging-common:$paging_version"

    // optional - RxJava support
    implementation "androidx.paging:paging-rxjava2:$paging_version"
}

六、Navigation

导航的依赖关系。

Navigation类已经在androidx.navigation包中，但目前依赖于Support Library 27.1.1和相关的Arch组件版本。 具有AndroidX依赖关系的导航版本将在未来发布。

dependencies {
    def nav_version = "1.0.0-alpha05"

    implementation "android.arch.navigation:navigation-fragment:$nav_version" // use -ktx for Kotlin
    implementation "android.arch.navigation:navigation-ui:$nav_version" // use -ktx for Kotlin

    // optional - Test helpers
    androidTestImplementation "android.arch.navigation:navigation-testing:$nav_version" // use -ktx for Kotlin
}

安全的args

对于Safe args，请在顶级build.gradle文件中添加以下类路径

buildscript {
    repositories {
        google()
    }
    dependencies {
        classpath "android.arch.navigation:navigation-safe-args-gradle-plugin:1.0.0-alpha05"
    }
}

并在您的应用程序或模块build.gradle文件中

apply plugin: "androidx.navigation.safeargs"

七、WorkManager

WorkManager的依赖关系。

WorkManager类已经在androidx.work包中，但目前依赖于Support Library 27.1和相关的Arch组件版本。 具有AndroidX依赖关系的WorkManager版本将在未来发布。

WorkManager需要compileSdk版本28或更高版本。

dependencies {
    def work_version = "1.0.0-alpha07"

    implementation "android.arch.work:work-runtime:$work_version" // use -ktx for Kotlin

    // optional - Firebase JobDispatcher support
    implementation "android.arch.work:work-firebase:$work_version"

    // optional - Test helpers
    androidTestImplementation "android.arch.work:work-testing:$work_version"
}