Android新手之旅(10) 嵌套布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/bk0">
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="180px"
        android:layout_marginLeft="60px" android:layout_marginTop="70px"
        >
        <Button android:background="@drawable/btn01" 
            android:text="" android:id="@+id/button1" 
            android:layout_width="wrap_content" android:layout_height="wrap_content" 
            >
        </Button>
        <Button android:background="@drawable/btn02" 
            android:text="" android:id="@+id/button2" 
            android:layout_width="wrap_content" android:layout_height="wrap_content" 
            >
        </Button>
    </LinearLayout>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="180px"
        android:layout_marginLeft="60px" android:layout_marginTop="0px"
        >
        <Button android:background="@drawable/btn03" 
            android:text="" android:id="@+id/button3" 
            android:layout_width="wrap_content" android:layout_height="wrap_content" 
            >
        </Button>
        <Button android:background="@drawable/btn04" 
            android:text="" android:id="@+id/button4" 
            android:layout_width="wrap_content" android:layout_height="wrap_content" 
            >
        </Button>
    </LinearLayout>
</LinearLayout>