Android ConstraintLayout约束布局的居中详解手机开发

Android ConstraintLayout约束布局的居中

xml代码：

<?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"> 
 
    <TextView 
        android:id="@+id/text1" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:background="@android:color/holo_red_light" 
        android:text="text1：顶部水平居中" 
        android:textColor="@android:color/white" 
        app:layout_constraintEnd_toEndOf="parent" 
        app:layout_constraintStart_toStartOf="parent" 
        app:layout_constraintTop_toTopOf="parent" /> 
 
    <TextView 
        android:id="@+id/text2" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:background="@android:color/holo_red_light" 
        android:text="text2：位于text1下且水平居中" 
        android:textColor="@android:color/white" 
        app:layout_constraintEnd_toEndOf="parent" 
        app:layout_constraintStart_toStartOf="parent" 
        app:layout_constraintTop_toBottomOf="@id/text1" /> 
 
    <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:background="@android:color/holo_green_light" 
        android:text="水平居中，且居于text2下" 
        android:textColor="@android:color/white" 
        app:layout_constraintEnd_toEndOf="parent" 
        app:layout_constraintStart_toStartOf="parent" 
        app:layout_constraintTop_toBottomOf="@id/text2" /> 
 
 
    <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:background="@android:color/holo_red_light" 
        android:text="居中位于底部" 
        android:textColor="@android:color/white" 
        app:layout_constraintBottom_toBottomOf="parent" 
        app:layout_constraintEnd_toEndOf="parent" 
        app:layout_constraintStart_toStartOf="parent" /> 
 
 
    <TextView 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:background="@android:color/holo_blue_bright" 
        android:text="全局居中" 
        android:textColor="@android:color/white" 
        app:layout_constraintBottom_toBottomOf="parent" 
        app:layout_constraintEnd_toEndOf="parent" 
        app:layout_constraintStart_toStartOf="parent" 
        app:layout_constraintTop_toTopOf="parent" /> 
</android.support.constraint.ConstraintLayout>

输出结果如图：