Android Support庫的源碼位置在sdk 目錄下
/Users/chanson.cc/Library/Android/sdk/extras/android/m2repository/com/android/support
support-v4-24.1.1-sources.jar是包含代碼的jar， 使用JD-GUI可以打開查看代碼。 從24.1.1 之後的就都是aar 的庫了， 無法再通過這種方式直接看源碼了。 但是仍然可以解壓aar， 查看裏面的class.jar 來查看。
~/Library/Android/sdk/extras/android/m2repository/com/android/support » ls chanson.cc@chansonccdeMacBook-Pro
animated-vector-drawable instantvideo preference-leanback-v17 support-core-ui support-v4
appcompat-v7 leanback-v17 preference-v14 support-core-utils support-vector-drawable
cardview-v7 mediarouter-v7 preference-v7 support-dynamic-animation test
customtabs multidex recommendation support-fragment transition
design multidex-instrumentation recyclerview-v7 support-media-compat wearable
exifinterface palette-v7 support-annotations support-tv-provider
gridlayout-v7 percent support-compat support-v13最後，當然還可以從 googlesource 裏查看代碼，
https://android.googlesource.com/platform/frameworks/support/+/jb-dev/v4/java/android/support/v4/view/ViewPager.java
或者從grepcode查看代碼
http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.0.1_r1/android/support/v4/view/ViewPager.java