好吧~dialog

Dialog dialog = new Dialog(RemindContentActivity.this, R.style.MyDialog);
dialog.setContentView(R.layout.remind_dialog);
Window mWindow = dialog.getWindow();
WindowManager.LayoutParams lp = mWindow.getAttributes();
lp.gravity = Gravity.BOTTOM;
lp.width = LayoutParams.MATCH_PARENT;
dialog.getWindow().setAttributes(lp);
dialog.show();

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical" 
    android:background="@null">
    <Button 
        android:id="@+id/remind_time_once"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#e0ffffff"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginBottom="1dp"
        />
    <Button 
        android:id="@+id/remind_time_repeat"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#e0ffffff"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        />
    <Button 
        android:id="@+id/remind_time_cancel"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="#e0ffffff"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginBottom="20dp"
        />
	
</LinearLayout>

<style name="MyDialog" parent="@android:Theme.Dialog">
        <item name="android:windowFrame">@null</item>
        <item name="android:windowNoTitle">true</item> 
        <item name="android:windowBackground">@android:color/transparent</item>
        <item name="android:windowIsFloating">true</item>
        <item name="android:windowContentOverlay">@null</item>
    </style>