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1.介绍

相信大家对Android Support Libray都不陌生，随着Android版本的快速迭代，Google推出了Support Libray用以兼容低版本的Android设备。但是随着版本越来越多，支持库的维护和使用也变得越来越复杂，于是AndroidX应运而生，接下来我们一起来学习下如何迁移到AndroidX吧！

AndroidX基于Android Support Libray 28.0.0版本进行迭代开发。

环境要求：

Android Studio 3.2.0及以上版本
compileSdkVersion 28及以上版本

2.迁移到AndroidX

在AS工具栏中点击Refactor——>Migrate to AndroidX选项，出现下面的提示框：

意思是说，在迁移之前建议先备份一下当前的项目，勾选【Backup project as Zip File】选项备份，然后点击【MIGRATE】按钮会提示选择一个备份路径，选择完成后会出现如下提示：

点击【DO REFACTOR】按钮，继续往下看：

出现一个警告，说没有搜索到要修改的代码，没关系，点击搜索之后，再次点击【DO REFACTOR】按钮就可以了，一阵编译过后迁移完成，此时编译一下整个工程，可能会提示一些类找不到的问题，重新导入一下就可以了。

注意：由于支持库升级到了AndroidX，一些使用了支持库的第三方库也需要升级到最新版本，比如rxlifecycle等，目前大部分主流第三方库都已经支持AndroidX了。

3.对比

看下和原来的项目有哪些区别：

dependencies

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

被修改成了：

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.0.2'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.0-alpha2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.1.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0'
}

可以看到com.android.support全部被修改成了androidx，版本号也改变了，同时项目中此依赖的引用包名也会被同时修改。

gradle.properties

增加了以下两个配置：

android.useAndroidX=true

设置true为时，Android插件会使用相应的AndroidX库而不是支持库，默认为false。
android.enableJetifier=true

设置true为时，Android插件会自动迁移现有的第三方库，通过重写其二进制文件来使用AndroidX，默认为false。

4.支持库迁移AndroidX速查表

Old build artifact	AndroidX build artifact
android.arch.core:common	androidx.arch.core:core-common:2.0.0-rc01
android.arch.core:core	androidx.arch.core:core:2.0.0-rc01
android.arch.core:core-testing	androidx.arch.core:core-testing:2.0.0-rc01
android.arch.core:runtime	androidx.arch.core:core-runtime:2.0.0-rc01
android.arch.lifecycle:common	androidx.lifecycle:lifecycle-common:2.0.0-rc01
android.arch.lifecycle:common-java8	androidx.lifecycle:lifecycle-common-java8:2.0.0-rc01
android.arch.lifecycle:compiler	androidx.lifecycle:lifecycle-compiler:2.0.0-rc01
android.arch.lifecycle:extensions	androidx.lifecycle:lifecycle-extensions:2.0.0-rc01
android.arch.lifecycle:livedata	androidx.lifecycle:lifecycle-livedata:2.0.0-rc01
android.arch.lifecycle:livedata-core	androidx.lifecycle:lifecycle-livedata-core:2.0.0-rc01
android.arch.lifecycle:reactivestreams	androidx.lifecycle:lifecycle-reactivestreams:2.0.0-rc01
android.arch.lifecycle:runtime	androidx.lifecycle:lifecycle-runtime:2.0.0-rc01
android.arch.lifecycle:viewmodel	androidx.lifecycle:lifecycle-viewmodel:2.0.0-rc01
android.arch.paging:common	androidx.paging:paging-common:2.0.0-rc01
android.arch.paging:runtime	androidx.paging:paging-runtime:2.0.0-rc01
android.arch.paging:rxjava2	androidx.paging:paging-rxjava2:2.0.0-rc01
android.arch.persistence.room:common	androidx.room:room-common:2.0.0-rc01
android.arch.persistence.room:compiler	androidx.room:room-compiler:2.0.0-rc01
android.arch.persistence.room:guava	androidx.room:room-guava:2.0.0-rc01
android.arch.persistence.room:migration	androidx.room:room-migration:2.0.0-rc01
android.arch.persistence.room:runtime	androidx.room:room-runtime:2.0.0-rc01
android.arch.persistence.room:rxjava2	androidx.room:room-rxjava2:2.0.0-rc01
android.arch.persistence.room:testing	androidx.room:room-testing:2.0.0-rc01
android.arch.persistence:db	androidx.sqlite:sqlite:2.0.0-rc01
android.arch.persistence:db-framework	androidx.sqlite:sqlite-framework:2.0.0-rc01
com.android.support.constraint:constraint-layout	androidx.constraintlayout:constraintlayout:1.1.2
com.android.support.constraint:constraint-layout-solver	androidx.constraintlayout:constraintlayout-solver:1.1.2
com.android.support.test.espresso.idling:idling-concurrent	androidx.test.espresso.idling:idling-concurrent:3.1.0
com.android.support.test.espresso.idling:idling-net	androidx.test.espresso.idling:idling-net:3.1.0
com.android.support.test.espresso:espresso-accessibility	androidx.test.espresso:espresso-accessibility:3.1.0
com.android.support.test.espresso:espresso-contrib	androidx.test.espresso:espresso-contrib:3.1.0
com.android.support.test.espresso:espresso-core	androidx.test.espresso:espresso-core:3.1.0
com.android.support.test.espresso:espresso-idling-resource	androidx.test.espresso:espresso-idling-resource:3.1.0
com.android.support.test.espresso:espresso-intents	androidx.test.espresso:espresso-intents:3.1.0
com.android.support.test.espresso:espresso-remote	androidx.test.espresso:espresso-remote:3.1.0
com.android.support.test.espresso:espresso-web	androidx.test.espresso:espresso-web:3.1.0
com.android.support.test.janktesthelper:janktesthelper	androidx.test.jank:janktesthelper:1.0.1
com.android.support.test.services:test-services	androidx.test:test-services:1.1.0
com.android.support.test.uiautomator:uiautomator	androidx.test.uiautomator:uiautomator:2.2.0
com.android.support.test:monitor	androidx.test:monitor:1.1.0
com.android.support.test:orchestrator	androidx.test:orchestrator:1.1.0
com.android.support.test:rules	androidx.test:rules:1.1.0
com.android.support.test:runner	androidx.test:runner:1.1.0
com.android.support:animated-vector-drawable	androidx.vectordrawable:vectordrawable-animated:1.0.0
com.android.support:appcompat-v7	androidx.appcompat:appcompat:1.0.0
com.android.support:asynclayoutinflater	androidx.asynclayoutinflater:asynclayoutinflater:1.0.0
com.android.support:car	androidx.car:car:1.0.0-alpha5
com.android.support:cardview-v7	androidx.cardview:cardview:1.0.0
com.android.support:collections	androidx.collection:collection:1.0.0
com.android.support:coordinatorlayout	androidx.coordinatorlayout:coordinatorlayout:1.0.0
com.android.support:cursoradapter	androidx.cursoradapter:cursoradapter:1.0.0
com.android.support:customtabs	androidx.browser:browser:1.0.0
com.android.support:customview	androidx.customview:customview:1.0.0
com.android.support:design	com.google.android.material:material:1.0.0-rc01
com.android.support:documentfile	androidx.documentfile:documentfile:1.0.0
com.android.support:drawerlayout	androidx.drawerlayout:drawerlayout:1.0.0
com.android.support:exifinterface	androidx.exifinterface:exifinterface:1.0.0
com.android.support:gridlayout-v7	androidx.gridlayout:gridlayout:1.0.0
com.android.support:heifwriter	androidx.heifwriter:heifwriter:1.0.0
com.android.support:interpolator	androidx.interpolator:interpolator:1.0.0
com.android.support:leanback-v17	androidx.leanback:leanback:1.0.0
com.android.support:loader	androidx.loader:loader:1.0.0
com.android.support:localbroadcastmanager	androidx.localbroadcastmanager:localbroadcastmanager:1.0.0
com.android.support:media2	androidx.media2:media2:1.0.0-alpha03
com.android.support:media2-exoplayer	androidx.media2:media2-exoplayer:1.0.0-alpha01
com.android.support:mediarouter-v7	androidx.mediarouter:mediarouter:1.0.0
com.android.support:multidex	androidx.multidex:multidex:2.0.0
com.android.support:multidex-instrumentation	androidx.multidex:multidex-instrumentation:2.0.0
com.android.support:palette-v7	androidx.palette:palette:1.0.0
com.android.support:percent	androidx.percentlayout:percentlayout:1.0.0
com.android.support:preference-leanback-v17	androidx.leanback:leanback-preference:1.0.0
com.android.support:preference-v14	androidx.legacy:legacy-preference-v14:1.0.0
com.android.support:preference-v7	androidx.preference:preference:1.0.0
com.android.support:print	androidx.print:print:1.0.0
com.android.support:recommendation	androidx.recommendation:recommendation:1.0.0
com.android.support:recyclerview-selection	androidx.recyclerview:recyclerview-selection:1.0.0
com.android.support:recyclerview-v7	androidx.recyclerview:recyclerview:1.0.0
com.android.support:slices-builders	androidx.slice:slice-builders:1.0.0
com.android.support:slices-core	androidx.slice:slice-core:1.0.0
com.android.support:slices-view	androidx.slice:slice-view:1.0.0
com.android.support:slidingpanelayout	androidx.slidingpanelayout:slidingpanelayout:1.0.0
com.android.support:support-annotations	androidx.annotation:annotation:1.0.0
com.android.support:support-compat	androidx.core:core:1.0.0
com.android.support:support-content	androidx.contentpager:contentpager:1.0.0
com.android.support:support-core-ui	androidx.legacy:legacy-support-core-ui:1.0.0
com.android.support:support-core-utils	androidx.legacy:legacy-support-core-utils:1.0.0
com.android.support:support-dynamic-animation	androidx.dynamicanimation:dynamicanimation:1.0.0
com.android.support:support-emoji	androidx.emoji:emoji:1.0.0
com.android.support:support-emoji-appcompat	androidx.emoji:emoji-appcompat:1.0.0
com.android.support:support-emoji-bundled	androidx.emoji:emoji-bundled:1.0.0
com.android.support:support-fragment	androidx.fragment:fragment:1.0.0
com.android.support:support-media-compat	androidx.media:media:1.0.0
com.android.support:support-tv-provider	androidx.tvprovider:tvprovider:1.0.0
com.android.support:support-v13	androidx.legacy:legacy-support-v13:1.0.0
com.android.support:support-v4	androidx.legacy:legacy-support-v4:1.0.0
com.android.support:support-vector-drawable	androidx.vectordrawable:vectordrawable:1.0.0
com.android.support:swiperefreshlayout	androidx.swiperefreshlayout:swiperefreshlayout:1.0.0
com.android.support:textclassifier	androidx.textclassifier:textclassifier:1.0.0
com.android.support:transition	androidx.transition:transition:1.0.0
com.android.support:versionedparcelable	androidx.versionedparcelable:versionedparcelable:1.0.0
com.android.support:viewpager	androidx.viewpager:viewpager:1.0.0
com.android.support:wear	androidx.wear:wear:1.0.0
com.android.support:webkit	androidx.webkit:webkit:1.0.0

5.一些问题

升级到AS 3.2版本后，Android Lint增加了一些代码检测项，其中最为明显的就是AndroidManifest.xml中的警告：

App is not indexable by Google Search; consider adding at least one Activity with an ACTION-VIEW intent filter. See issue explanation for more details.

意思是当前APP不支持Google搜索，需要至少在一个Activity中添加intent filter，没问题，满足你：

<action android:name="android.intent.action.VIEW" />

但是因为万里长城的原因，添加了这个filter也没什么用，不添加的话满页的黄色波浪又看着闹心，我们还可以这样做：

在app的build.gradle中添加一个警告忽略：

android {
    ...

    lintOptions {
        disable 'GoogleAppIndexingWarning'
    }
}

或者在AndroidManifest.xml中的application项中添加一下忽略也可以：

tools:ignore="GoogleAppIndexingWarning"

6.写在最后

到这里，AndroidX升级相关的内容就学习完了，希望对你能够有所帮助，如果你在升级AndroidX的过程中，遇到了一些其他的问题，欢迎给我留言。