简单实现Android弹出菜单效果

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:id="@+id/item1"
     android:title="item 1" />  
  <item android:id="@+id/item1"
     android:title="item 2" /> 
  <item android:id="@+id/item1"
     android:title="item 3" />
</menu> 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">
  <Button
    android:id="@+id/popupButton"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/showPopup" />
</LinearLayout> 

using Android.App;
using Android.OS;
using Android.Widget;

namespace ch05demos.SrcActivity
{
  [Activity(Label = "Demo07PopupMenu")]
  public class Demo07PopupMenu : Activity
  {
    protected override void OnCreate(Bundle savedInstanceState)
    {
      base.OnCreate(savedInstanceState);
      SetContentView(Resource.Layout.demo07_Popup);

      Button btn = FindViewById<Button>(Resource.Id.popupButton);
      btn.Click += (s, arg) =>
      {
        PopupMenu menu = new PopupMenu(this, btn);
        menu.Inflate(Resource.Menu.demo07_popup_menu);
        menu.MenuItemClick += (sender, args) =>
        {
          string str = string.Format("你选择了：{0}", args.Item);
          Toast.MakeText(this,str, ToastLength.Short).Show();
        };
        menu.DismissEvent += (sender, args) =>
        {
          //菜单消失后可在此事件中做一些后续处理
        };
        menu.Show();
      };
    }
  }
}