xml中设置按钮获取焦点，按压，正常时的背景。并经过圆角处理。
<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="https://schemas.android.com/apk/res/android"> <item android:state_focused="true"> <shape> <corners android:radius="2dp" /> <solid android:color="#FF0064D2" /> </shape> </item> <item android:state_pressed="true"> <shape> <corners android:radius="2dp" /> <solid android:color="#FF0064D2" /> </shape> </item> <item> <shape> <corners android:radius="2dp" /> <solid android:color="#FF0079FF" /> </shape> </item></selector><?xml vers
