我没有完全实现 MultiDex 支持，所以我的一些类不在正确的 dex 文件中.要修复它，您必须做的不仅仅是在 defaultConfig 块中设置 multiDexEnabled = true.您还必须:

I was incompletely implementing MultiDex support, so some of my classes weren't in the proper dex file. To fix it, you have to do more than just set multiDexEnabled = true in your defaultConfig block. You also have to:

1. 在依赖项中包含 compile 'com.android.support:multidex:1.0.1'
2. 让您的应用程序类扩展 MultiDexApplication 而不仅仅是 Application.或者，您可以在应用程序的 attachBaseContext() 中调用 MultiDex.install().

1. Include compile 'com.android.support:multidex:1.0.1' in your dependencies
2. Have your Application class extend MultiDexApplication instead of just Application. Alternatively, you can call MultiDex.install() in attachBaseContext() of your application.

见 https://developer.android.com/tools/building/multidex.html更多详情.