<RatingBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintStart_toStartOf="parent"
android:numStars="5"
android:stepSize="1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="@id/submit_area"
/>
自定义和监听：https://www.runoob.com/w3cnote/android-tutorial-ratingbar.html
