【ActionBar】
The ActionBar APIs were first added in Android 3.0 (API level 11) but they are also available in the Support Library for compatibility with Android 2.1 (API level 7) and above.
Caution: Be certain you import the ActionBar class (and related APIs) from the appropriate package:
- If supporting API levels lower than 11:
import android.support.v7.app.ActionBar - If supporting only API level 11 and higher:
import android.app.ActionBar
AppCompatActivity- Adds an application activity class that can be used as a base class for activities that use the Support Library action bar implementation.
参考：http://android.xsoftlab.net/guide/topics/ui/actionbar.html
