NoApp/app/src/main/res/layout/activity_login.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"
    tools:context="cn.gov.gxch.abc.noapp.LoginActivity">

    <EditText
        android:id="@+id/txt_account"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/label_account"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/label_account"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="账号"
        app:layout_constraintBottom_toBottomOf="@+id/txt_account"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/txt_passwd"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:inputType="textPassword"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/label_passwd"
        app:layout_constraintTop_toBottomOf="@+id/txt_account" />

    <TextView
        android:id="@+id/label_passwd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginStart="8dp"
        android:text="密码"
        app:layout_constraintBottom_toBottomOf="@+id/txt_passwd"
        app:layout_constraintStart_toStartOf="parent" />

    <EditText
        android:id="@+id/txt_vcode"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:ems="10"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toStartOf="@+id/btn_get_vcode"
        app:layout_constraintStart_toEndOf="@+id/label_vcode"
        app:layout_constraintTop_toBottomOf="@+id/txt_passwd" />

    <TextView
        android:id="@+id/label_vcode"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginStart="8dp"
        android:text="验证码"
        app:layout_constraintBottom_toBottomOf="@+id/txt_vcode"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/btn_get_vcode"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:text="获取验证码"
        android:textSize="12sp"
        app:layout_constraintBottom_toBottomOf="@+id/txt_vcode"
        app:layout_constraintEnd_toEndOf="parent" />

    <Button
        android:id="@+id/btn_login"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="登录"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/txt_vcode" />

</android.support.constraint.ConstraintLayout>