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。

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>

只是把你的两个textviews主机和端口在一个独立的线性布局水平和使用android:layout_weight使百分比

检查https://github.com/mmin18/FlexLayout，你可以使用百分比或java表达式直接在布局xml。

<EditText
    app:layout_left="0%"
    app:layout_right="60%"
    app:layout_height="wrap_content"/>
<EditText
    app:layout_left="prev.right+10dp"
    app:layout_right="100%"
    app:layout_height="wrap_content"/>

不能在RelativeLayout中使用百分比来定义视图的维度。最好的方法是使用线性布局和权重，或自定义布局。

我已经解决了这个问题，创建一个自定义视图:

public class FractionalSizeView extends View {
  public FractionalSizeView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  public FractionalSizeView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int width = MeasureSpec.getSize(widthMeasureSpec);
    setMeasuredDimension(width * 70 / 100, 0);
  }
}

这是不可见的支柱，我可以用它来对齐RelativeLayout中的其他视图。