======自定义Spinner======

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    xmlns:app="https://schemas.android.com/apk/res/com.example.myviewdemo"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <Spinner
        android:id="@+id/field_item_spinner_content"
       
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:animationCache="true"
        android:drawSelectorOnTop="true"
        android:dropDownSelector="@drawable/selector_spinner"
        android:spinnerMode="dropdown" />

</LinearLayout><?xml version="1.0" encoding="utf-8"?>
<LinearLayo