两个LinearLayout或者ConstraintLayout平分布局

两个LinearLayout平分布局如图所示：

代码如下,有需要的可以直接复制粘贴到activity_main.xml，之后可以在布局上增加自己想要的控件

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:id="@+id/linearlayout"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_marginBottom="8dp"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/linearlayout2"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="1.0">


    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearlayout2"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_marginBottom="8dp"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/linearlayout"
        app:layout_constraintTop_toTopOf="parent">

    </LinearLayout>
</android.support.constraint.ConstraintLayout>

下面是用ConstraintLayout平分布局，代码如下：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <android.support.constraint.ConstraintLayout
        android:id="@+id/constraintLayout1"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/constraintLayout2"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

    </android.support.constraint.ConstraintLayout>

    <android.support.constraint.ConstraintLayout
        android:id="@+id/constraintLayout2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/constraintLayout1"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.495">

    </android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>