虚线.Alert.只有底部有边框.清空图片资源

虚线：

<shape
    android:shape="line"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <!--<stroke
        android:dashGap="6dp"
        android:dashWidth="10dp"
        android:width="2dp"
        android:color="#97d914" />

    &lt;!&ndash; 虚线的高度 &ndash;&gt;
    <size android:height="1dp" />-->

    <stroke
        android:width="3px"
        android:color="#4f4e4e"
        android:dashWidth="10px"
        android:dashGap="10px" />

</shape>

下划线必须属性
 android:layerType="software"

//        清空图片资源
        mPublicImage.mPublicImage.setWillNotDraw(true);

AlertDialog：

AlertDialog.Builder builder = new AlertDialog.Builder(MySettingActivity.this);
                builder.setTitle("确认退出？")
                        .setNegativeButton("取消",null)
                        .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(MySettingActivity.this, "lalalalalala", Toast.LENGTH_SHORT).show();
                            }
                        }).show();

设置只有底部有边框

//思路大概是先创建一个灰色的drawable,之后用白色的drawable遮挡,再把白色的drawable下移1dp
<?xml version="1.0" encoding="UTF-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <!-- 边框颜色值 -->
    <item>
        <shape>
            <solid android:color="#000000" />
        </shape>
    </item>
   <item android:bottom="1dp"> <!--设置只有底部有边框-->
        <shape>
            <solid android:color="#ffffff" />
        </shape>
    </item>
</layer-list>

//阴影效果原理同上
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- Bottom 2dp Shadow -->
    <item>
        <shape  android:shape="rectangle">
            <solid android:color="#BBB" />
            <corners android:radius="5dp" />
        </shape>
    </item>

    <!-- White Top color -->
    <item android:bottom="3px">
        <shape  android:shape="rectangle">
            <solid android:color="#FFE0EEEE" />
            <corners android:radius="5dp" />
            <padding
                android:top="15dp"
                android:right="15dp"
                android:bottom="15dp"
                android:left="15dp"/>
        </shape>
    </item>
</layer-list>

//        清空图片资源 
        .setWillNotDraw(true);
        mPublicImage.setWillNotDraw(true);