<activity android:name=".CustomDialogActivity" android:theme="@style/Theme.CustomDialog" />
Theme.CustomDialog
<style name="Theme.CustomDialog" parent="android:style/Theme.Dialog">
<item name="android:windowBackground">@drawable/filled_box</item>
</style>
filled_box.xml
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<!-- <solid android:color="#f0600000" /> -->
<gradient android:startColor="#000" android:endColor="#fff" />
<stroke android:width="20dp" color="#ffff8080" android:dashWidth="5dp"
android:dashGap="3dp" />
<corners android:radius="10dp" />
<padding android:left="20dp" android:top="50dp" android:right="20dp"
android:bottom="50dp" />
</shape>
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还可以让TextView变成提示框
requestWindowFeature(Window.FEATURE_LEFT_ICON);
getWindow().setFeatureDrawableResource(Window.FEATURE_LEFT_ICON,android.R.drawable.ic_dialog_alert);
<TextView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/text"
android:layout_width="match_parent" android:layout_height="match_parent"
android:gravity="center_vertical|center_horizontal"
android:text="注意"/>