android相对布局实例—登录界面

<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:layout_margin="20dp"
    tools:context=".MainActivity" >
    
    <TextView 
        android:id="@+id/Txttitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:gravity="center_horizontal"
        android:layout_alignParentRight="true"
        android:text="登录界面"/>

    <EditText
        android:id="@+id/username"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/Txttitle"
        android:layout_alignRight="@id/Txttitle"
        android:layout_below="@id/Txttitle" 
        android:layout_marginTop="20dp"
        android:hint="username"/>
    <EditText 
        android:id="@+id/password"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/username"
        android:layout_alignLeft="@id/username"
        android:layout_alignRight="@id/username"
         android:layout_marginTop="20dp"
        android:hint="password"
        android:inputType="textCapWords"/>

</RelativeLayout>