Android - RelativeLayout布局

RelativeLayout布局

本文地址:http://blog.csdn.net/caroline_wendy

RelativeLayout是一种相对布局方式，是根据属性进行对齐；A Layout where the positions of the children can be described in relation to each other or to the parent.在布局中，子控件的位置根据相互之间的关系进行描述。Note that you cannot have a circular dependency between the size of the RelativeLayout and the position of its children. 子控件之间不能存在循环依赖。
Note: In platform version 17 and lower, RelativeLayout was affected by a measurement bug that could cause child views to be measured with incorrect MeasureSpec values. This was triggered when a RelativeLayout container was placed in a scrolling container, such as a ScrollView or HorizontalScrollView. If a custom view not equipped to properly measure with the MeasureSpec mode UNSPECIFIED was placed in a RelativeLayout, this would silently work anyway as RelativeLayout would pass a very large AT_MOST MeasureSpec instead.This behavior has been preserved for apps that set android:targetSdkVersion="17" or older in their manifest's uses-sdk tag for compatibility. Apps targeting SDK version 18 or newer will receive the correct behavior

属性名称	描述
android:layout_below	摆放在指定组件的下边
android:layout_toLeftOf	摆放在指定组件的左边
android:layout_toRightOf	摆放在指定组件的右边
android:layout_alignTop	以指定组件作为参考进行上对齐
android:layout_algnBottom	以指定组件作为参照进行下对齐
android:layout_alignLeft	以指定组件作为参考进行左对齐
android:layout_alignRight	以指定组件

 
android:layout_toStartOf="@+id/buttonTweet” //表是在某个控件的前对齐，如果不知道，就图形界面拖动

<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".StatusActivity">

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/button_tweet"
android:id="@+id/buttonTweet"
android:layout_alignParentEnd="true"/>

<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textMultiLine"
android:ems="10"
android:id="@+id/editText"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:hint="@string/hint_status"
android:layout_toStartOf="@+id/buttonTweet"/>

<TextView
android:id="@+id/textCount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignEnd="@id/buttonTweet"
android:layout_below="@id/buttonTweet"
android:text="140"
android:textAppearance="?android:textAppearanceSmall"/>

</RelativeLayout>