在drawable中创建xml，例如dialog_bg.xml

Create a xml in drawable , say dialog_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid
        android:color="@color/white"/>
    <corners
        android:radius="30dp" />
    <padding
        android:left="10dp"
        android:top="10dp"
        android:right="10dp"
        android:bottom="10dp" />
</shape>

将其设置为布局xml中的背景

set it as the background in your layout xml

android:background="@drawable/dialog_bg"

将对话框的根视图的背景设置为透明，因为Android会将对话框布局放置在根视图中，该视图隐藏了自定义布局中的各个角.

Set the background of the dialog's root view to transparent, because Android puts your dialog layout within a root view that hides the corners in your custom layout.

dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));