Android Gradle 失败 多个 dex 文件定义 okhttp

Question

>我有以下依赖关系：

dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:25.3.1'
compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-moshi:2.3.0'
compile('com.github.eoinsha:JavaPhoenixChannels:0.2') {
exclude module: 'groovy-all'
}
}

以及以下依赖树：

+--- com.android.support:appcompat-v7:25.3.1
|    +--- com.android.support:support-annotations:25.3.1
|    +--- com.android.support:support-v4:25.3.1
|    |    +--- com.android.support:support-compat:25.3.1
|    |    |    --- com.android.support:support-annotations:25.3.1
|    |    +--- com.android.support:support-media-compat:25.3.1
|    |    |    +--- com.android.support:support-annotations:25.3.1
|    |    |    --- com.android.support:support-compat:25.3.1 (*)
|    |    +--- com.android.support:support-core-utils:25.3.1
|    |    |    +--- com.android.support:support-annotations:25.3.1
|    |    |    --- com.android.support:support-compat:25.3.1 (*)
|    |    +--- com.android.support:support-core-ui:25.3.1
|    |    |    +--- com.android.support:support-annotations:25.3.1
|    |    |    --- com.android.support:support-compat:25.3.1 (*)
|    |    --- com.android.support:support-fragment:25.3.1
|    |         +--- com.android.support:support-compat:25.3.1 (*)
|    |         +--- com.android.support:support-media-compat:25.3.1 (*)
|    |         +--- com.android.support:support-core-ui:25.3.1 (*)
|    |         --- com.android.support:support-core-utils:25.3.1 (*)
|    +--- com.android.support:support-vector-drawable:25.3.1
|    |    +--- com.android.support:support-annotations:25.3.1
|    |    --- com.android.support:support-compat:25.3.1 (*)
|    --- com.android.support:animated-vector-drawable:25.3.1
|         --- com.android.support:support-vector-drawable:25.3.1 (*)
+--- com.squareup.retrofit2:retrofit:2.3.0
|    --- com.squareup.okhttp3:okhttp:3.8.0
|         --- com.squareup.okio:okio:1.13.0
+--- com.squareup.retrofit2:converter-moshi:2.3.0
|    +--- com.squareup.retrofit2:retrofit:2.3.0 (*)
|    --- com.squareup.moshi:moshi:1.4.0
|         --- com.squareup.okio:okio:1.11.0 -> 1.13.0
--- com.github.eoinsha:JavaPhoenixChannels:0.2
+--- com.fasterxml.jackson.core:jackson-databind:2.8.3
|    +--- com.fasterxml.jackson.core:jackson-annotations:2.8.0
|    --- com.fasterxml.jackson.core:jackson-core:2.8.3
--- com.squareup.okhttp3:okhttp-ws:3.4.1
--- com.squareup.okhttp3:okhttp:3.4.1 -> 3.8.0 (*)

尝试构建项目时出现此错误：

Error:Execution failed for task ':app:transformClassesWithDexForDebug'.
> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.dex.DexException: Multiple dex files define Lokhttp3/internal/ws/WebSocketReader$FrameCallback;

这应该是由于类路径上存在两个不同版本的 okhttp 库引起的：

• 3.4.1com.squareup.okhttp3:okhttp-ws这是JavaPhoenixChannels的依赖

  关系

• 3.8.0 通过改造

Gradle 应该能够自动解决此问题，所以我想知道问题出在哪里。 我试图通过将okhttp和okhttp-ws从它们各自的第一类依赖项中排除并单独编译它们来修复它，但这似乎没有帮助。

关于为什么会弹出此类错误的一些解释也值得赞赏。

Answer 1

正如@Selvin在评论中指出的那样，该问题是由于自 3.5 版以来okhtt-ws已移至核心项目内部，因此指定较新版本的okhttp和旧版本的okhttp-ws将导致okhttp-ws库的两个不同副本最终出现在类路径上。对于gradle，这些将是使用相同的包层次结构的不同库，因此它不会自动排除一个。

TL;DR 通过排除okhttp-ws依赖项来修复错误，因为它已在okhttp本身的 3.8 版中可用：

compile 'com.squareup.okhttp3:okhttp:3.8.0'
compile('com.github.eoinsha:JavaPhoenixChannels:0.2') {
exclude module: 'okhttp-ws'
}