sheishuoAPP/app/res/layout/login_and_reg_layout.xml

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.sheishuo.app.login.LoginAndRegActivity">

    <ImageView
        android:id="@+id/activity_login_an_reg_logo"
        android:layout_width="100dp"
        android:layout_height="100dp"
        app:srcCompat="@drawable/logo"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginTop="64dp"
        android:layout_marginLeft="8dp"
        app:layout_constraintLeft_toLeftOf="parent"
        android:layout_marginRight="8dp"
        app:layout_constraintRight_toRightOf="parent" />

    <TextView
        android:id="@+id/tv_app_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SHEI SHUO"
        android:typeface="sans"
        android:layout_marginLeft="8dp"
        app:layout_constraintLeft_toLeftOf="@+id/activity_login_an_reg_logo"
        android:layout_marginTop="8dp"
        app:layout_constraintTop_toBottomOf="@+id/activity_login_an_reg_logo"
        android:layout_marginRight="8dp"
        app:layout_constraintRight_toRightOf="@+id/activity_login_an_reg_logo" />

    <Button
        android:id="@+id/btn_login"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="登录"
        style="@style/NormalBtnStyle"
        android:layout_marginLeft="0dp"
        app:layout_constraintLeft_toLeftOf="@+id/tv_app_name"
        android:layout_marginRight="0dp"
        app:layout_constraintRight_toRightOf="@+id/tv_app_name"
        android:layout_marginTop="56dp"
        app:layout_constraintTop_toBottomOf="@+id/tv_app_name" />

    <Button
        android:id="@+id/btn_register"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="注册"
        style="@style/NormalBtnStyle"
        android:layout_marginLeft="8dp"
        app:layout_constraintLeft_toLeftOf="@+id/btn_login"
        android:layout_marginRight="8dp"
        app:layout_constraintRight_toRightOf="@+id/btn_login"
        android:layout_marginTop="25dp"
        app:layout_constraintTop_toBottomOf="@+id/btn_login" />



</android.support.constraint.ConstraintLayout>