.net上传图片功能

Question

public string UpLoadImage(HtmlInputFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight)
    { 
        string sThumbFile = "";
        string sFilename = ""; 
        sSavePath = "UpLoad/";
        sThumbExtension = "_thumb";
        
        
        if (upImage.PostedFile != null)
        {
            HttpPostedFile myFile = upImage.PostedFile;
            int nFileLen = myFile.ContentLength;
            if (nFileLen == 0)
            {
                return "没有选择上传图片";
            }            string extendName = System.IO.Path.GetExtension(myFile.FileName).ToLower();            if (extendName != ".jpg" && extendName != ".jpge" && extendName != ".gif" && extendName != ".bmp")
            {
                return "图片格式不正确";
            }            byte[] myData = new Byte[nFileLen];
            myFile.InputStream.Read(myData, 0, nFileLen);
           
            sFilename = System.IO.Path.GetFileName(myFile.FileName);
            int file_append = 0;
            while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))
            {
                file_append++;
                sFilename = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName)
                    + file_append.ToString() + extendName;//".jpg";
            }
           
            System.IO.FileStream newFile
                = new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename),
                System.IO.FileMode.Create, System.IO.FileAccess.Write);
            newFile.Write(myData, 0, myData.Length);
            newFile.Close();
          
            System.Drawing.Image.GetThumbnailImageAbort myCallBack =
                new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
            System.Drawing.Bitmap myBitmap;
            try
            {
                myBitmap = new System.Drawing.Bitmap(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename));
                if(intThumbWidth==0)
                    intThumbWidth = myBitmap.Width;
                if(intThumbHeight==0)
                    intThumbHeight = myBitmap.Height;
                file_append = 0;
                sThumbFile = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName)
                    + sThumbExtension + extendName;//".jpg";
                while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)))
                {
                    file_append++;
                    sThumbFile = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) +
                        file_append.ToString() + sThumbExtension + extendName;// ".jpg";
                }                
                System.Drawing.Image myThumbnail
                    = myBitmap.GetThumbnailImage(intThumbWidth,
                    intThumbHeight, myCallBack, IntPtr.Zero);
                myThumbnail.Save(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)); 
                myThumbnail.Dispose();
                myBitmap.Dispose();
            }
            catch
            {  
                System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename));
                return "图片格式不正确";
            }
            return sThumbFile;
        }
        return "没有选择图片";
    }
    public bool ThumbnailCallback()
    {
        return false;
    }