android原生的Spinner提供了下拉列表选项框，但在一些流行的APP中，原生的Spinner似乎不太受待见，而通常会有下图所示的下拉列表选项框：

初始化状态：

点击弹出下拉选择选项框：

选中后：

注意那个指示箭头，如果把这个控件写的比较精细的话，在下拉-选择-复位过程中箭头是应该有动画旋转效果的。

这种样式的选择框实现方案很多，并且常见、常用，我自己写了一个，我写的这个例子的代码运行结果就是上图所示。

首先是MainActivity.Java：

package zhangphil.app;

import android.content.Context;

import android.graphics.Color;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.support.v7.widget.ListPopupWindow;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.ArrayAdapter;

import android.widget.ImageView;

import android.widget.LinearLayout;

import android.widget.PopupWindow;

import android.widget.TextView;

import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

private ListPopupWindow listPopupWindow = null;

private ImageView arrowImageView;

private TextView chooseText;

private LinearLayout linearLayout;

private SortAadapter adapter = null;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

linearLayout= (LinearLayout) findViewById(R.id.linearLayout);

arrowImageView = (ImageView)findViewById(R.id.arrow);

chooseText= (TextView) findViewById(R.id.chooseText);

linearLayout.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

showListPopupWindow(linearLayout);

}

});

}

private class SortAadapter extends ArrayAdapter {

private String[] strs = {"最新", "推荐", "全部", "最热"};

private LayoutInflater inflater;

private int res;

public SortAadapter(Context context, int resource) {

super(context, resource);

inflater = LayoutInflater.from(context);

res = resource;

}

@Override

public View getView(int position, View convertView, ViewGroup parent) {

if (convertView == null)

convertView = inflater.inflate(res, null);

TextView text = (TextView) convertView.findViewById(android.R.id.text1);

text.setText(getItem(position));

text.setTextColor(Color.WHITE);

text.setTextSize(10);

convertView.setBackgroundColor(Color.RED);

return convertView;

}

@Override

public String getItem(int position) {

return strs[position];

}

@Override

public int getCount() {

return strs.length;

}

}

public void showListPopupWindow(View view) {

if (listPopupWindow == null)

listPopupWindow = new ListPopupWindow(this);

if (adapter == null) {

adapter = new SortAadapter(this, android.R.layout.simple_list_item_1);

// ListView适配器

listPopupWindow.setAdapter(adapter);

// 选择item的监听事件

listPopupWindow.setOnItemClickListener(new AdapterView.OnItemClickListener() {

@Override

public void onItemClick(AdapterView> parent, View view, int pos, long id) {

Toast.makeText(getApplicationContext(), adapter.getItem(pos), Toast.LENGTH_SHORT).show();

chooseText.setText(adapter.getItem(pos));

listPopupWindow.dismiss();

}

});

listPopupWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {

@Override

public void onDismiss() {

//旋转0度是复位ImageView

arrowImageView.animate().setDuration(500).rotation(0).start();

}

});

}

// ListPopupWindow的锚,弹出框的位置是相对当前View的位置

listPopupWindow.setAnchorView(view);

listPopupWindow.setVerticalOffset(dip2px(this,5));

// 对话框的宽高

listPopupWindow.setWidth(view.getWidth());

listPopupWindow.setModal(true);

listPopupWindow.show();

arrowImageView.animate().setDuration(500).rotation(180).start();

}

public static int dip2px(Context context, float dipValue) {

float sDensity = context.getResources().getDisplayMetrics().density;

final float scale = sDensity;

return (int) (dipValue * scale + 0.5f);

}

}

布局文件：

android:layout_width="match_parent"

android:layout_height="match_parent">

android:id="@+id/linearLayout"

android:layout_width="wrap_content"

android:layout_height="24dp"

android:background="@drawable/round_corner_line_radius_3dp"

android:orientation="horizontal"

android:paddingLeft="8dp"

android:paddingRight="8dp"

android:layout_centerInParent="true">

android:id="@+id/chooseText"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center_vertical"

android:text="分类"

android:textColor="@android:color/holo_orange_dark"

android:textSize="12dp" />

android:id="@+id/arrow"

android:layout_width="14dp"

android:layout_height="14dp"

android:layout_gravity="center_vertical"

android:layout_marginLeft="8dp"

android:src="@drawable/icon" />

LinearLayout的背景需要一个圆角背景res/drawable/round_corner_line_radius_3dp.xml：

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

android:shape= "rectangle">

android:width="2px"/>

箭头icon.png：

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