有趣的是，基于@olefevre的回答，人们不仅可以使用“隐形struts”进行50/50的布局，而且还可以使用涉及2的幂的各种布局。

例如，这里有一个布局，将宽度切割成四个相等的部分(实际上是三个，权重为1,1,2):

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <View
        android:id="@+id/strut"
        android:layout_width="1dp"
        android:layout_height="match_parent"
        android:layout_centerHorizontal="true"
        android:background="#000000" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_toLeftOf="@+id/strut" >

        <View
            android:id="@+id/left_strut"
            android:layout_width="1dp"
            android:layout_height="match_parent"
            android:layout_toLeftOf="@+id/strut"
            android:layout_centerHorizontal="true"
            android:background="#000000" />

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignRight="@+id/left_strut"
            android:text="Far Left" />

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:layout_toRightOf="@+id/left_strut"
            android:text="Near Left" />
    </RelativeLayout>

        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_alignLeft="@id/strut"
            android:layout_alignParentRight="true"
            android:text="Right" />

</RelativeLayout>

这并没有完全回答最初的问题，即70/30分割，但在组件之间50/50分割的特殊情况下，有一种方法:在中心放置一个无形的支柱，并用它来定位感兴趣的两个组件。

<RelativeLayout 
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <View android:id="@+id/strut"
        android:layout_width="0dp"
        android:layout_height="0dp" 
        android:layout_centerHorizontal="true"/>
    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignRight="@id/strut"
        android:layout_alignParentLeft="true"
        android:text="Left"/> 
    <Button 
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@id/strut"
        android:layout_alignParentRight="true"
        android:text="Right"/>
</RelativeLayout>

由于这是一个非常常见的情况，这个解决方案不仅仅是一个好奇。这有点笨拙，但很有效，因为空的、零大小的支柱应该花费很少。

但总的来说，最好不要对现有的Android布局抱有太多期望……

你正在寻找android:layout_weight属性。它将允许你使用百分比来定义你的布局。

在下面的例子中，左键占用70%的空间，右键占用30%的空间。

<LinearLayout
    android:layout_width="match_parent" 
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <Button
        android:text="left" 
        android:layout_width="0dp" 
        android:layout_height="wrap_content" 
        android:layout_weight=".70" /> 

    <Button
        android:text="right" 
        android:layout_width="0dp" 
        android:layout_height="wrap_content" 
        android:layout_weight=".30" />

</LinearLayout>

它的工作原理与任何类型的视图相同，你可以用一些EditText替换按钮来满足你的需要。

请确保将layout_width设置为0dp，否则您的视图可能无法正确缩放。

注意，权重和不一定等于1，我只是觉得这样读起来更容易。你可以将第一个权重设置为7，第二个权重设置为3，结果是一样的。

PercentRelativeLayout在支持库26.0.0版中已弃用。

谷歌引入了新的名为ConstraintLayout的布局。

将库作为依赖项添加到模块级构建中。gradle文件:

     dependencies {
        compile 'com.android.support.constraint:constraint-layout:1.0.1'
      }

只需添加一个布局文件:

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.support.constraint.ConstraintLayout>

约束

约束帮助您保持小部件的一致性。您可以使用锚(例如下面所示的约束句柄)来确定不同小部件之间的对齐规则。

Wrap Content: The view expands as needed to fit its contents. Match Constraints: The view expands as needed to meet the definition of its constraints after accounting for margins. However, if the given dimension has only one constraint, then the view expands to fit its contents. Using this mode on either the height or width also allows you to set a size ratio. Fixed: You specify a specific dimension in the text box below or by resizing the view in the editor. Spread: The views are evenly distributed (after margins are accounted for). This is the default. Spread inside: The first and last view are affixed to the constraints on each end of the chain and the rest are evenly distributed. Weighted: When the chain is set to either spread or spread inside, you can fill the remaining space by setting one or more views to "match constraints" (0dp). By default, the space is evenly distributed between each view that's set to "match constraints," but you can assign a weight of importance to each view using the layout_constraintHorizontal_weight and layout_constraintVertical_weight attributes. If you're familiar with layout_weight in a linear layout, this works the same way. So the view with the highest weight value gets the most amount of space; views that have the same weight get the same amount of space. Packed: The views are packed together (after margins are accounted for). You can then adjust the whole chain's bias (left/right or up/down) by changing the chain's head view bias. Center Horizontally or Center Vertically: To create a chain of views quickly, select them all, right-click one of the views, and then select either Center Horizontally or Center Vertically, to create either a horizontal or vertical chain Baseline alignment: Align the text baseline of a view to the text baseline of another view. Constrain to a guideline: You can add a vertical or horizontal guideline to which you can constrain views, and the guideline will be invisible to app users. You can position the guideline within the layout based on either dp units or percent, relative to the layout's edge. Adjust the constraint bias: When you add a constraint to both sides of a view (and the view size for the same dimension is either "fixed" or "wrap content"), the view becomes centered between the two constraints with a bias of 50% by default. You can adjust the bias by dragging the bias slider in the Properties window Set size as a ratio: You can set the view size to a ratio such as 16:9 if at least one of the view dimensions is set to "match constraints" (0dp).

你可以从官方医生那里了解更多。

你可以通过布局权重来实现。权重决定了屏幕上无人认领的部分如何划分。给每个EditText一个0的layout_width和一些成比例的权重。也就是说，如果你想让第一个占用两倍的空间，给一个权重为2，给另一个权重为1。

更新1

正如@EmJiHash指出的那样，PercentRelativeLayout在API级别26.0.0中已弃用

以下引用谷歌的评论:

这个类在API级别26.0.0中已弃用。 可以考虑使用ConstraintLayout和相关的布局。下面展示了如何使用ConstraintLayout复制百分比布局的功能

谷歌引入了名为android.support.percent的新API

然后，您可以指定百分比，以采取的视图

添加编译依赖项，如

implementation 'com.android.support:percent:22.2.0

在这里，PercentRelativeLayout是我们可以做的百分比布局

 <android.support.percent.PercentRelativeLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
     <ImageView
         app:layout_widthPercent="50%"
         app:layout_heightPercent="50%"
         app:layout_marginTopPercent="25%"
         app:layout_marginLeftPercent="25%"/>
 </android.support.percent.PercentRelativeLayout>