<?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="match_parent"> <Button android:id="@+id/butn" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="发送广播" /> </LinearLayout>