android:supportsRtl="true"

AndroidStudio新建工程的AndroidManifest文件里会有一个supportsRtl属性，并且默认是true，那这个属性到底有什么用呢，顾名思义就是“支持RTL”

官方文档：android:supportsRtl

Declares whether your application is willing to support right-to-left (RTL) layouts.

If set to true and targetSdkVersion is set to 17 or higher, various RTL APIs will be activated and used by the system so your app can display RTL layouts. If set to false or if targetSdkVersion is set to 16 or lower, the RTL

APIs will be ignored or will have no effect and your app will behave the same regardless of the layout direction ass ociated to the user's Locale choice (your layouts will always be left-to-right).

The default value of this attribute is false.

This attribute was added in API level 17.