可用来观摩学习的开源安卓应用
http://blog.interstellr.com/post/39321551640/14-great-android-apps-that-are-also-open-source

https://en.wikipedia.org/wiki/List_of_free_and_open-source_Android_applications

https://github.com/c99koder/lastfm-android

https://github.com/cattong/YiBo