activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<Button
android:id="@+id/btn_01"
android:layout_centerInParent="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="按钮1111111\n222222\n333333" />
<Button
android:layout_alignTop="@id/btn_01"
android:layout_toRightOf="@id/btn_01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="按钮2" />
<Button
android:layout_alignBottom="@id/btn_01"
android:layout_toLeftOf="@id/btn_01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="按钮3" />
<Button
android:layout_alignLeft="@id/btn_01"
android:layout_below="@id/btn_01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="按钮4"/>
<Button
android:layout_alignRight="@id/btn_01"
android:layout_above="@id/btn_01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="按钮5"/>
</RelativeLayout>
