android base layout – top middle bottom

Android upper, middle and lower layout, and the middle part is automatically filled.

The code is as follows, of which the bold red sentences are key:

<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"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <!-- 顶部开始 -->
    <RelativeLayout
        android:id="@+id/layout_top"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_alignParentTop="true"
        android:background="#ff0000" >

        <TextView
            android:id="@+id/tv_top"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true"
            android:text="@string/str_top" />
    </RelativeLayout>
    <!-- 顶部结束 -->
    <!-- 底部开始 -->
    <RelativeLayout
        android:id="@+id/layout_bottom"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:layout_alignParentBottom="true"
        android:background="#00ffff" >
        <TableRow
            android:id="@+id/tr_bottom"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center_horizontal|center_vertical"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true" >
            <Button
                android:id="@+id/btn_modify"
                android:layout_width="120dp"
                android:layout_height="wrap_content"
                android:text="@string/str_modify" />
            <Button
                android:id="@+id/btn_back"
                android:layout_width="120dp"
                android:layout_height="wrap_content"
                android:text="@string/str_back" />
        </TableRow>
        <TextView 
            android:layout_width="0dp"
            android:layout_height="0dp" />
    </RelativeLayout>
    <!-- 底部结束 -->
    <!-- 中间开始 -->
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/layout_bottom"
        android:layout_below="@id/layout_top" >
        <TextView
            android:id="@+id/tv_middle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/str_middle" />
    </ScrollView>
    <!-- 中间结束 -->

</RelativeLayout>

design sketch:

Reproduced at: https://www.cnblogs.com/xl0715/p/3424526.html