如何正确减少应用程序方法数（低于 dex 限制）

Question

我开始使用大量使用 firebase 功能和支持库的新应用。我很快就达到了 65k dex 的限制，尽管考虑到应用程序的简单性，我没有理由应该在那里。我知道我需要排除某些我没有用的依赖项，所以我一直在使用 gradlew app:dependencies 来分析依赖项并拉出不止一次拉入的东西或我不需要的东西。

尽管有很多 excludes，但我无法显着减少方法计数（仅 3%）。我只是坚持使用 multi-dex 吗？如果不是，我如何有效地减少方法计数？

更多信息：

minSdk 19

这是 build.gradle 依赖块的 before/after 和 gradlew app:dependencies output。我很高兴 post dexcount 文本输出每个库有多少方法，如果这有帮助的话。我可以说，方法计数的最大贡献者是支持库和 com.google.common.* 和 com.google.android.gms.*

瘦身前

应用中的方法总数-debug.apk：67707（已使用 103.31%）

瘦身后

应用中的方法总数-debug.apk：65852（已使用 100.48%）

之前：build.gradle 依赖块（不排除）

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:multidex:1.0.2'
    implementation "com.android.support:appcompat-v7:$supportLibraryVersion"
    implementation "com.android.support:recyclerview-v7:$supportLibraryVersion"
    implementation "com.android.support:design:$supportLibraryVersion"
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation "com.android.support:cardview-v7:$supportLibraryVersion"
    implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'
    implementation 'io.reactivex.rxjava2:rxjava:2.1.5'
    implementation('com.oakwoodsc.rxfirestore:rxfirestore-debug:1.0@aar') {
        exclude group: 'io.reactivex.rxjava2', module: 'rxandroid'
        exclude group: 'io.reactivex.rxjava2', module: 'rxjava'
    }
    implementation 'com.firebaseui:firebase-ui-auth:3.1.0' // Remove once custom version
    implementation "com.google.android.gms:play-services-location:$firebaseVersion"
    implementation "com.google.firebase:firebase-firestore:$firebaseVersion"
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}

之前：gradlew app:dependencies输出

大量重复！

+--- com.google.firebase:firebase-core:11.4.2
|    \--- com.google.firebase:firebase-analytics:11.4.2
|         +--- com.google.android.gms:play-services-basement:11.4.2
|         |    +--- com.android.support:support-v4:25.2.0 -> 26.1.0
|         |    |    +--- com.android.support:support-compat:26.1.0
|         |    |    |    +--- com.android.support:support-annotations:26.1.0
|         |    |    |    \--- android.arch.lifecycle:runtime:1.0.0
|         |    |    |         +--- android.arch.lifecycle:common:1.0.0
|         |    |    |         \--- android.arch.core:common:1.0.0
|         |    |    +--- com.android.support:support-media-compat:26.1.0
|         |    |    |    +--- com.android.support:support-annotations:26.1.0
|         |    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|         |    |    +--- com.android.support:support-core-utils:26.1.0
|         |    |    |    +--- com.android.support:support-annotations:26.1.0
|         |    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|         |    |    +--- com.android.support:support-core-ui:26.1.0
|         |    |    |    +--- com.android.support:support-annotations:26.1.0
|         |    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|         |    |    \--- com.android.support:support-fragment:26.1.0
|         |    |         +--- com.android.support:support-compat:26.1.0 (*)
|         |    |         +--- com.android.support:support-core-ui:26.1.0 (*)
|         |    |         \--- com.android.support:support-core-utils:26.1.0 (*)
|         |    \--- com.google.android.gms:play-services-basement-license:11.4.2
|         +--- com.google.firebase:firebase-common:11.4.2
|         |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|         |    +--- com.google.android.gms:play-services-tasks:11.4.2
|         |    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|         |    |    \--- com.google.android.gms:play-services-tasks-license:11.4.2
|         |    \--- com.google.firebase:firebase-common-license:11.4.2
|         +--- com.google.firebase:firebase-analytics-impl:11.4.2
|         |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|         |    +--- com.google.firebase:firebase-iid:11.4.2
|         |    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|         |    |    +--- com.google.firebase:firebase-common:11.4.2 (*)
|         |    |    \--- com.google.firebase:firebase-iid-license:11.4.2
|         |    +--- com.google.firebase:firebase-common:11.4.2 (*)
|         |    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|         |    \--- com.google.firebase:firebase-analytics-impl-license:11.4.2
|         \--- com.google.firebase:firebase-analytics-license:11.4.2
+--- com.android.support:multidex:1.0.2
+--- com.android.support:appcompat-v7:26.1.0
|    +--- com.android.support:support-annotations:26.1.0
|    +--- com.android.support:support-v4:26.1.0 (*)
|    +--- com.android.support:support-vector-drawable:26.1.0
|    |    +--- com.android.support:support-annotations:26.1.0
|    |    \--- com.android.support:support-compat:26.1.0 (*)
|    \--- com.android.support:animated-vector-drawable:26.1.0
|         +--- com.android.support:support-vector-drawable:26.1.0 (*)
|         \--- com.android.support:support-core-ui:26.1.0 (*)
+--- com.android.support:recyclerview-v7:26.1.0
|    +--- com.android.support:support-annotations:26.1.0
|    +--- com.android.support:support-compat:26.1.0 (*)
|    \--- com.android.support:support-core-ui:26.1.0 (*)
+--- com.android.support:design:26.1.0
|    +--- com.android.support:support-v4:26.1.0 (*)
|    +--- com.android.support:appcompat-v7:26.1.0 (*)
|    +--- com.android.support:recyclerview-v7:26.1.0 (*)
|    \--- com.android.support:transition:26.1.0
|         +--- com.android.support:support-annotations:26.1.0
|         \--- com.android.support:support-v4:26.1.0 (*)
+--- com.android.support.constraint:constraint-layout:1.0.2 -> 1.1.0-beta1
|    \--- com.android.support.constraint:constraint-layout-solver:1.1.0-beta1
+--- com.android.support:cardview-v7:26.1.0
|    \--- com.android.support:support-annotations:26.1.0
+--- io.reactivex.rxjava2:rxandroid:2.0.1
|    \--- io.reactivex.rxjava2:rxjava:2.0.1 -> 2.1.5
|         \--- org.reactivestreams:reactive-streams:1.0.1
+--- io.reactivex.rxjava2:rxjava:2.1.5 (*)
+--- com.oakwoodsc.rxfirestore:rxfirestore-debug:1.0
+--- com.firebaseui:firebase-ui-auth:3.1.0
|    +--- com.android.support:design:26.1.0 (*)
|    +--- com.android.support:customtabs:26.1.0
|    |    +--- com.android.support:support-compat:26.1.0 (*)
|    |    \--- com.android.support:support-annotations:26.1.0
|    +--- com.android.support.constraint:constraint-layout:1.1.0-beta1 (*)
|    +--- com.google.firebase:firebase-auth:11.4.2
|    |    +--- com.google.android.gms:play-services-base:11.4.2
|    |    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    |    |    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|    |    |    \--- com.google.android.gms:play-services-base-license:11.4.2
|    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    |    +--- com.google.firebase:firebase-common:11.4.2 (*)
|    |    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|    |    \--- com.google.firebase:firebase-auth-license:11.4.2
|    +--- com.google.android.gms:play-services-auth:11.4.2
|    |    +--- com.google.android.gms:play-services-auth-api-phone:11.4.2
|    |    |    +--- com.google.android.gms:play-services-base:11.4.2 (*)
|    |    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    |    |    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|    |    |    \--- com.google.android.gms:play-services-auth-api-phone-license:11.4.2
|    |    +--- com.google.android.gms:play-services-auth-base:11.4.2
|    |    |    +--- com.google.android.gms:play-services-base:11.4.2 (*)
|    |    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    |    |    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|    |    |    \--- com.google.android.gms:play-services-auth-base-license:11.4.2
|    |    +--- com.google.android.gms:play-services-base:11.4.2 (*)
|    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    |    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|    |    \--- com.google.android.gms:play-services-auth-license:11.4.2
|    \--- com.android.support:cardview-v7:26.1.0 (*)
+--- com.google.android.gms:play-services-location:11.4.2
|    +--- com.google.android.gms:play-services-base:11.4.2 (*)
|    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
|    \--- com.google.android.gms:play-services-location-license:11.4.2
\--- com.google.firebase:firebase-firestore:11.4.2
     +--- com.google.android.gms:play-services-basement:11.4.2 (*)
     +--- com.google.firebase:firebase-common:11.4.2 (*)
     +--- com.google.android.gms:play-services-tasks:11.4.2 (*)
     +--- com.squareup.okhttp:okhttp:2.7.2
     |    \--- com.squareup.okio:okio:1.6.0
     \--- com.google.guava:guava:20.0

之后：build.gradle 依赖块（完全排除）

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation("com.google.android.gms:play-services-base:$playServicesVersion") {
        exclude group: "com.android.support", module: "support-v4"
    }
    implementation 'com.android.support:multidex:1.0.2'
    implementation "com.android.support:design:$supportLibraryVersion"
    implementation("com.firebaseui:firebase-ui-auth:3.1.0") {  // Remove once custom version
        exclude group: "com.google.android.gms", module: "play-services-base"
        exclude group: "com.google.android.gms", module: "play-services-basement"
        exclude group: "com.google.android.gms", module: "play-services-tasks"
        exclude group: "com.android.support", module: "design"
        exclude group: "com.android.support", module: "support-compat"
        exclude group: "com.android.support", module: "support-annotations"
        exclude group: "com.android.support", module: "cardview-v7"
    }
    implementation("com.android.support:cardview-v7:$supportLibraryVersion") {
        exclude group: "com.android.support", module: "support-annotations"
    }
    implementation('com.oakwoodsc.rxfirestore:rxfirestore-debug:1.0@aar') {
        exclude group: 'io.reactivex.rxjava2', module: 'rxandroid'
        exclude group: 'io.reactivex.rxjava2', module: 'rxjava'
    }
    implementation("com.google.android.gms:play-services-location:$playServicesVersion") {
        exclude group: "com.google.android.gms", module: "play-services-base"
        exclude group: "com.google.android.gms", module: "play-services-tasks"
        exclude group: "com.google.android.gms", module: "play-services-basement"
    }
    implementation("com.google.firebase:firebase-firestore:$playServicesVersion") {
        exclude group: "com.google.android.gms", module: "play-services-basement"
        exclude group: "com.google.android.gms", module: "play-services-tasks"
    }
    implementation 'io.reactivex.rxjava2:rxandroid:2.0.1'
    implementation 'io.reactivex.rxjava2:rxjava:2.1.5'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}

之后：gradlew app:dependencies输出：

减少重复...

+--- com.google.android.gms:play-services-base:11.4.2
|    +--- com.google.android.gms:play-services-basement:11.4.2
|    |    \--- com.google.android.gms:play-services-basement-license:11.4.2
|    +--- com.google.android.gms:play-services-tasks:11.4.2
|    |    +--- com.google.android.gms:play-services-basement:11.4.2 (*)
|    |    \--- com.google.android.gms:play-services-tasks-license:11.4.2
|    \--- com.google.android.gms:play-services-base-license:11.4.2
+--- com.android.support:multidex:1.0.2
+--- com.android.support:design:26.1.0
|    +--- com.android.support:support-v4:26.1.0
|    |    +--- com.android.support:support-compat:26.1.0
|    |    |    +--- com.android.support:support-annotations:26.1.0
|    |    |    \--- android.arch.lifecycle:runtime:1.0.0
|    |    |         +--- android.arch.lifecycle:common:1.0.0
|    |    |         \--- android.arch.core:common:1.0.0
|    |    +--- com.android.support:support-media-compat:26.1.0
|    |    |    +--- com.android.support:support-annotations:26.1.0
|    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|    |    +--- com.android.support:support-core-utils:26.1.0
|    |    |    +--- com.android.support:support-annotations:26.1.0
|    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|    |    +--- com.android.support:support-core-ui:26.1.0
|    |    |    +--- com.android.support:support-annotations:26.1.0
|    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|    |    \--- com.android.support:support-fragment:26.1.0
|    |         +--- com.android.support:support-compat:26.1.0 (*)
|    |         +--- com.android.support:support-core-ui:26.1.0 (*)
|    |         \--- com.android.support:support-core-utils:26.1.0 (*)
|    +--- com.android.support:appcompat-v7:26.1.0
|    |    +--- com.android.support:support-annotations:26.1.0
|    |    +--- com.android.support:support-v4:26.1.0 (*)
|    |    +--- com.android.support:support-vector-drawable:26.1.0
|    |    |    +--- com.android.support:support-annotations:26.1.0
|    |    |    \--- com.android.support:support-compat:26.1.0 (*)
|    |    \--- com.android.support:animated-vector-drawable:26.1.0
|    |         +--- com.android.support:support-vector-drawable:26.1.0 (*)
|    |         \--- com.android.support:support-core-ui:26.1.0 (*)
|    +--- com.android.support:recyclerview-v7:26.1.0
|    |    +--- com.android.support:support-annotations:26.1.0
|    |    +--- com.android.support:support-compat:26.1.0 (*)
|    |    \--- com.android.support:support-core-ui:26.1.0 (*)
|    \--- com.android.support:transition:26.1.0
|         +--- com.android.support:support-annotations:26.1.0
|         \--- com.android.support:support-v4:26.1.0 (*)
+--- com.firebaseui:firebase-ui-auth:3.1.0
|    +--- com.android.support:customtabs:26.1.0
|    +--- com.android.support.constraint:constraint-layout:1.1.0-beta1
|    |    \--- com.android.support.constraint:constraint-layout-solver:1.1.0-beta1
|    +--- com.google.firebase:firebase-auth:11.4.2
|    |    +--- com.google.firebase:firebase-common:11.4.2
|    |    |    \--- com.google.firebase:firebase-common-license:11.4.2
|    |    \--- com.google.firebase:firebase-auth-license:11.4.2
|    \--- com.google.android.gms:play-services-auth:11.4.2
|         +--- com.google.android.gms:play-services-auth-api-phone:11.4.2
|         |    \--- com.google.android.gms:play-services-auth-api-phone-license:11.4.2
|         +--- com.google.android.gms:play-services-auth-base:11.4.2
|         |    \--- com.google.android.gms:play-services-auth-base-license:11.4.2
|         \--- com.google.android.gms:play-services-auth-license:11.4.2
+--- com.android.support:cardview-v7:26.1.0
+--- com.oakwoodsc.rxfirestore:rxfirestore-debug:1.0
+--- com.google.android.gms:play-services-location:11.4.2
|    \--- com.google.android.gms:play-services-location-license:11.4.2
+--- com.google.firebase:firebase-firestore:11.4.2
|    +--- com.google.firebase:firebase-common:11.4.2 (*)
|    +--- com.squareup.okhttp:okhttp:2.7.2
|    |    \--- com.squareup.okio:okio:1.6.0
|    \--- com.google.guava:guava:20.0
+--- io.reactivex.rxjava2:rxandroid:2.0.1
|    \--- io.reactivex.rxjava2:rxjava:2.0.1 -> 2.1.5
|         \--- org.reactivestreams:reactive-streams:1.0.1
\--- io.reactivex.rxjava2:rxjava:2.1.5 (*)

Answer 1

首先，您不需要所有这些 exclude。如果两个依赖使用com.android.support:support-v4:26.1.0，它只包含一次。它被列出两次，所以你可以看到谁依赖它。

您可能要考虑的一个选项是 turning on ProGuard。这将删除所有未使用的代码，包括库代码。在你的情况下，它可能会让你低于 65k 限制。

要使用它，请在 build.gradle 中进行设置：发布 { minifyEnabled 真 proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' }

您需要创建 proguard-rules.pro 并使用特定于您的应用程序的一些指令填充它。请务必查看完整文档，了解您可能需要在其中包含的内容。

虽然在没有 ProGuard 的情况下保持在 65k 限制以下是可能的，但大多数中等复杂度的应用程序会很快超过它，而且我发现避免像 AppCompat 这样的库以努力保持在 65k 限制以下是通常比它值得的工作更多。

即使使用 ProGuard，一些应用程序也会遇到 65k 的限制。其他应用程序可能出于某种原因不想使用 ProGuard。在这些情况下，您最好的选择是 enable multidex，这样您就可以超过 65k 的限制。

Answer 2

Proguard 是解决您问题的关键。确保您应用的 build.gradle 文件在 buildtypes

下有以下内容

buildTypes {
    //debug
    //staging
    release {
        minifyEnabled true
        shrinkResources true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

在我的例子中，我的发布版本缩小了代码，缩减了资源，最重要的是使用混淆器来减少其他库带来的代码膨胀。可以复制代码proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

观看 David East 精彩的 short video 关于 Proguard 的好处。

此外，如果您还没有查看 Proguard 文档

如何正确减少应用程序方法数（低于 dex 限制）

How to properly reduce an app method count (below dex-limit)

dependencies

android

build.gradle

android-multidex