一定要看的 Android 资源目录的相关知识 raw drwable values
http://blog.csdn.net/shichexixi/article/details/5985677
http://developer.android.com/guide/topics/resources/index.html
http://developer.android.com/guide/topics/resources/accessing-resources.html
http://developer.android.com/guide/topics/resources/available-resources.html