安卓圆角Button

<?xml version="1.0" encoding="UTF-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="false">        <shape android:shape="rectangle" >            <!-- 填充的颜色 -->            <solid android:color="@color/nav_bg"></solid>            <!-- 设置按钮的四个角为弧形 -->            <!-- android:radius 弧形的半径 -->            <corners android:radius="15dip" />            <!-- padding：Button里面的文字与Button边界的间隔 -->            <padding android:bottom="2dp" android:left="2dp" android:right="2dp" android:top="2dp" />        </shape>    </item>    <item android:state_pressed="true">        <shape android:shape="rectangle">            <solid android:color="@color/nav_bg" />            <corners android:radius="15dip" />        </shape>    </item></selector>