安卓巢狀佈局

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    tools:context="com.example.admin.frame.MainActivity">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@mipmap/background"
        android:orientation="vertical"
        android:gravity="center">

        <LinearLayout
            android:layout_width="360dp"
            android:layout_height="190dp"
            android:background="@mipmap/a1"
            android:layout_marginTop="5dp"
            android:layout_marginBottom="5dp"></LinearLayout>

        <LinearLayout
            android:layout_width="360dp"
            android:layout_height="120dp"
            android:background="@mipmap/a2"
            android:layout_marginBottom="5dp"
            android:gravity="center">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="歡迎來到安卓程式設計世界-"
                android:textColor="#ff0000"
                android:textSize="25dp"
                />
        </LinearLayout>

        <LinearLayout
            android:layout_width="360dp"
            android:layout_height="wrap_content"
            android:background="@mipmap/a3"
            android:layout_marginBottom="5dp"
            android:orientation="horizontal"
            android:gravity="center"
            >

            <LinearLayout
                android:layout_width="100dp"
                android:layout_height="wrap_content"
                android:background="@mipmap/b1"
                android:layout_marginRight="10dp"></LinearLayout>

            <LinearLayout
                android:layout_width="100dp"
                android:layout_height="wrap_content"
                android:background="@mipmap/b2"
                android:layout_marginRight="10dp"></LinearLayout>

            <LinearLayout
                android:layout_width="100dp"
                android:layout_height="wrap_content"
                android:background="@mipmap/b3"></LinearLayout>
        </LinearLayout>
    </LinearLayout>


</android.support.constraint.ConstraintLayout>