RalativeLayout_exc

<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="com.example.homework05.MainActivity" >

    <RelativeLayout 
        android:layout_width="fill_parent"
        android:layout_height="50dp">
        <!-- 城市 -->
        <!-- drawableLeft:在文字左边设置图标 -->
        <TextView 
            android:id="@+id/city"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
               android:drawableLeft="@drawable/city"
               android:text="北京"
               android:gravity="center"/>
        <!-- 扫一扫 -->
        <!-- android:adjustViewBounds="true" 是否调整自己的边界来保 持所显示图片的长宽比-->
        <ImageView 
            android:id="@+id/image_scan"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:src="@drawable/codescan"
            android:layout_alignParentRight="true"
            android:adjustViewBounds="true"/>
        <!-- 搜索编辑框 -->
        <EditText
            android:id="@+id/edit"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:hint="请输入。。。"
            android:layout_toRightOf="@id/city"
            android:layout_toLeftOf="@id/image_scan"/>
        <!-- 搜索图标-->
        <ImageView 
            android:id="@+id/image_search"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:src="@drawable/home_search_icon"
            android:layout_alignRight="@id/edit"
            android:layout_centerVertical="true"/>
    </RelativeLayout>
    <!-- 右下角的购物车 -->
    <ImageView
        android:id="@+id/image_buy"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:src="@drawable/buy"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"/>
    <!-- 下面的标签选项 -->
    <!--  android:button="@null"不显示单选按钮的圆圈 -->
    <RadioGroup 
        android:id="@+id/group"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_alignParentBottom="true"
        android:layout_toLeftOf="@id/image_buy"
        android:weightSum="4"
        android:orientation="horizontal">
        <RadioButton 
            android:id="@+id/btn_home"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="首页"
            android:gravity="center"
            android:button="@null"
            android:checked="true"
            android:drawableTop="@drawable/select_home"
            />
         <RadioButton 
            android:id="@+id/btn_person"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="分类"
            android:gravity="center"
            android:button="@null"
            android:drawableTop="@drawable/select_person"
            />
          <RadioButton 
            android:id="@+id/btn_new"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="新品"
            android:gravity="center"
            android:button="@null"
            android:drawableTop="@drawable/select_new"
            />
           <RadioButton 
            android:id="@+id/btn_search"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="match_parent"
            android:text="搜索"
            android:gravity="center"
            android:button="@null"
            android:drawableTop="@drawable/select_search"
            />
    </RadioGroup>
    
</RelativeLayout>