xamarin android——数据绑定到控件（二）

private void InitGallery()
        {
            Gallery gallery = FindViewById<Gallery> (Resource.Id.gallery);
            gallery.Adapter = new ImageAdapter (this);
        }

public class ImageAdapter:BaseAdapter
    {
        private Context context;

        public ImageAdapter(Context context)
        {
            this.context = context;
        }

        #region implemented abstract members of BaseAdapter
        public override Java.Lang.Object GetItem (int position)
        {
            ImageCursor.MoveToPosition (position);
            return ImageCursor.GetString (0);
        }
        public override long GetItemId (int position)
        {
            return position;
        }
        public override View GetView (int position, View convertView, ViewGroup parent)
        {
　　　　　　　//避免不断的销毁和创建新视图
            if (convertView == null) {
                ImageView imageView = new ImageView (context);
                ImageCursor.MoveToPosition (position);
                var imageUrl = ImageCursor.GetString (0);
                Console.WriteLine (imageUrl);
　　　　　　      //根据输出判断 MediaStore.Images.Media.InterfaceConst.Data 查询结果为图片路径
                //imageView.SetImageURI (Android.Net.Uri.WithAppendedPath(MediaStore.Images.Media.ExternalContentUri,imageID));
                imageView.SetImageURI (Android.Net.Uri.Parse(imageUrl));
                imageView.SetScaleType (ImageView.ScaleType.FitCenter);
                return imageView;
            } else {
                return convertView as ImageView;
            }
        }
        public override int Count {
            get {
                return ImageCursor.Count;
            }
        }
        #endregion

        private Android.Database.ICursor imageCursor;
        public Android.Database.ICursor ImageCursor {
            get{
                if (imageCursor==null) {
                    imageCursor = GetImageCursor ();
                }
                return imageCursor;
            }
            set{ imageCursor = value; }
        }

        //查询本机图片
        private Android.Database.ICursor GetImageCursor(){
            return (context as Activity).ManagedQuery (MediaStore.Images.Media.ExternalContentUri,
                new string[] {MediaStore.Images.Media.InterfaceConsts.Data},null,null,null);
        }
    }