安卓 style=“?android:attr/progressBarStyleSmall”表示的含义

对于能够显示文字的控件（如TextView EditText RadioButton Button CheckBox Chronometer等等），有时需要控制字体的大小。Android平台定义了三种字体大小。

"?android:attr/textAppearanceLarge"

"?android:attr/textAppearanceMedium"

"?android:attr/textAppearanceSmall"

使用方法为：

android:textAppearance="?android:attr/textAppearanceLarge" 
android:textAppearance="?android:attr/textAppearanceMedium" 
android:textAppearance="?android:attr/textAppearanceSmall"

或

style="?android:attr/textAppearanceLarge" 
style="?android:attr/textAppearanceMedium" 
style="?android:attr/textAppearanceSmall"