如何在旋转器中设置下拉箭头？

Question

    import android.os.Bundle;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.ArrayAdapter;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Spinner;
    import android.widget.AdapterView.OnItemSelectedListener;
    import android.widget.Toast;

        public class topup extends Activity  {
            Spinner spinner,spin1,spin2,spin3;
                EditText ed,ed1;
                Button btn;
                List<String> list, list1,list2,list3;
                    private String[] countries_list={"01","02","03","04","05","06","07","08","09","10","11","12"};

                    protected void onCreate(Bundle savedInstanceState) {
                        super.onCreate(savedInstanceState);
                        setContentView(R.layout.topup);


                        spinner = (Spinner) findViewById(R.id.spinner1);
                        spin1= (Spinner) findViewById(R.id.spinner2);
                        spin2= (Spinner) findViewById(R.id.spinner3);
                        spin3= (Spinner) findViewById(R.id.spinner4);
                        ed = (EditText) findViewById(R.id.editText3);

                        list = new ArrayList<String>();
                        list.add("");
                        list.add("select");
                        list.add("01");
                        list.add("02");
                        list.add("03");
                        list.add("04");
                        list.add("05");
                        list.add("06");
                        list.add("07");
                        list.add("08");
                        list.add("09");
                        list.add("10");
                        list.add("11");
                        list.add("12");

                        ArrayAdapter<String> adp = new ArrayAdapter<String>
                            (this, android.R.layout.simple_spinner_item, list);
                        //adp.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

                        spinner.setAdapter(adp);


                        spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

                            //@Override
                            public void onItemSelected(AdapterView<?> parent, View arg1,int arg2, long arg3) {
                                // TODO Auto-generated method stub
                                 String item = spinner.getItemAtPosition(1).toString();
                                 //Toast.makeText(spinner.getContext(), "Selected: " + item, Toast.LENGTH_LONG).show();
                                 String ss=spinner.getSelectedItem().toString();
                                 String 
                            }


                            public void onNothingSelected(AdapterView<?> arg0) {
                                // TODO Auto-generated method stub

                            }
                        });

我的xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/back1"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="wrap_content"
        android:layout_height="55dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="20dp" 
        android:background="@drawable/red">

        <Spinner
            android:id="@+id/spinner1"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:dropDownWidth="fill_parent" 
         />

    </LinearLayout>

    <EditText
        android:id="@+id/editText1"
        android:layout_width="wrap_content"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/linearLayout1"
        android:layout_alignRight="@+id/linearLayout1"
        android:layout_below="@+id/linearLayout1"
        android:layout_marginTop="25dp"
        android:background="@drawable/red"
        android:ems="10"
        android:hint="enter card number" >

        <requestFocus />
    </EditText>

    <LinearLayout
        android:id="@+id/linearLayout2"
        android:layout_width="wrap_content"
        android:layout_height="55dp"
        android:layout_alignLeft="@+id/editText1"
        android:layout_alignRight="@+id/editText1"
        android:layout_below="@+id/editText1"
        android:layout_marginTop="33dp"
        android:orientation="horizontal" 
        android:background="@drawable/red">

        <Spinner
            android:id="@+id/spinner3"
            android:layout_width="72dp"
            android:layout_height="wrap_content"
             />

        <Spinner
            android:id="@+id/spinner2"
            android:layout_width="72dp"
            android:layout_height="wrap_content" 
            />

        <EditText
            android:id="@+id/editText2"
            android:layout_width="22dp"
            android:layout_height="match_parent"
            android:layout_weight="0.18"
            android:ems="10"
            android:hint="enter cvv" />

    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout3"
        android:layout_width="wrap_content"
        android:layout_height="55dp"
        android:layout_alignParentLeft="true"
        android:layout_alignRight="@+id/linearLayout2"
        android:layout_below="@+id/linearLayout2"
        android:layout_marginTop="26dp"
        android:orientation="vertical"
        android:background="@drawable/red" >
    </LinearLayout>

    <Spinner
        android:id="@+id/spinner4"
        android:layout_width="15dp"
        android:layout_height="18dp"
        android:layout_alignBottom="@+id/linearLayout3"
        android:layout_alignLeft="@+id/linearLayout3"
        android:layout_alignRight="@+id/linearLayout3"
        android:layout_alignTop="@+id/linearLayout3"

      />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/linearLayout3"
        android:layout_marginTop="18dp"
        android:text="Add Amount" 
        android:background="@drawable/buttonsty"/>



</RelativeLayout>

Answer 1

基本上，需要为旋转器创建一个自定义背景。应该是这样的：

spinner_background.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item>

        <layer-list>

            <item>
                <color
                    android:color="@android:color/white"/>
            </item>

            <item>
                <bitmap
                    android:gravity="center_vertical|right"
                    android:src="@drawable/ic_arrow_drop_down_black_24dp"/>
            </item>

        </layer-list>

    </item>

</selector>

然后为您的旋转器创建一个自定义样式，其中您将上面的选择器指定为背景：

<style name="Widget.App.Spinner" parent="@style/Widget.AppCompat.Spinner">
    <item name="overlapAnchor">true</item>
    <item name="android:background">@drawable/spinner_background</item>
</style>

<item name="spinnerStyle">@style/Widget.App.Spinner</item>
<item name="android:spinnerStyle">@style/Widget.App.Spinner</item>