TextView设置字重

<TextView
                android:id="@+id/total_mileage"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:text="设置textview字重"/>

关键代码为：

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