上傳圖片處理 C#

using System;
using System.Web;
using System.Web.UI;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace {
    /// <summary>
    /// UploadFile 的摘要說明。
    /// </summary>
    public class UploadFile
    {
        public UploadFile()
        {
            //
            // TODO: 在此處添加建構函式邏輯
            //
        }
     
        /// <summary>
        /// 指定路徑 圖片大小
        /// </summary>
        /// <param name="dir"></param>
        /// <param name="width"></param>
        /// <param name="height"></param>
        /// <returns></returns>
 public string GetSqlFile(string dir, int width, int height)
  {
   string sqlfile="";
   string path = HttpContext.Current.Request.PhysicalApplicationPath.ToString()+"upload/";
   path +=dir;
   if(Directory.Exists(path))
   {

   }
   else
   {
    Directory.CreateDirectory(path);
   }
   if(Directory.Exists(path+"/small"))
   {

   }
   else
   {
    Directory.CreateDirectory(path+"/small");
   }
       HttpFileCollection files = HttpContext.Current.Request.Files;
  
 
       if(files[0].FileName.ToString().Length>0)
       {
        string filename = files[0].FileName.ToString();
        string datestr  = DateTime.Now.ToString("yyyyMMddHmmssfff");
        string ext     = filename.Substring(filename.LastIndexOf("."));
        if(ext!=".bmp"&&ext!=".jpg"&&ext!=".gif"&&ext!=".jpeg")
        {
         HttpContext.Current.Response.Write("<script>alert('上傳的檔案不是.gif,jpg,jpeg,bmp格式')</script>");
         return "";
        }
        files[0].SaveAs(path+"/"+datestr+ext);
        #region 產生小圖
        string originalFilename = path+"/"+datestr+ext;
     
        //縮小的倍數
        int iScale = 1;
        //從檔案取得圖片對象
        Image image = null;
        try
        {
             image = Image.FromFile(originalFilename);
        }
        catch
        {
           //
            try
            { 
                File.Delete(originalFilename);
                image.Dispose();
            
            }
            catch
            {
               
              
            }
            HttpContext.Current.Response.Write("<script>alert('上傳的檔案不是.gif,jpg,jpeg,bmp圖片的標準格式格式')</script>");
            return "";
           
        }
       
  
        int hi =0;
        int wi =0;

        wi=width;
 
        hi=height;
  
        Size size = new Size(wi,hi);
        //建立一個bmp圖片
        Image bitmap = new Bitmap(size.Width, size.Height);
        //建立一個畫板
        Graphics g = Graphics.FromImage(bitmap);
        //設定高品質插值法
        g.InterpolationMode = InterpolationMode.High;
        //設定高品質,低速度呈現平滑程度
        g.SmoothingMode = SmoothingMode.HighQuality;
        //清空一下畫布
        g.Clear(Color.Blue);
        //在指定位置畫圖
        g.DrawImage(image, new Rectangle(0, 0, bitmap.Width, bitmap.Height), new Rectangle(0, 0, image.Width, image.Height), GraphicsUnit.Pixel);
        if (ext == ".jpg" || ext == ".jpeg")
         bitmap.Save(path+"/small/"+datestr+ext, ImageFormat.Jpeg);
        if (ext == ".gif")
         bitmap.Save(path+"/small/"+datestr+ext, ImageFormat.Gif);
        if(ext==".bmp")
         bitmap.Save(path+"/small/"+datestr+ext,ImageFormat.Bmp);
        image.Dispose();
        bitmap.Dispose();
        g.Dispose();
        #endregion
        sqlfile=datestr+ext;
     
            try
            {
             image.Dispose();
             bitmap.Dispose();
             g.Dispose();
           
            }
            catch(Exception ex)
            {
             string exc = ex.Message.ToString();
             HttpContext.Current.Response.Write("<script>alert('"+exc+"');</script>");
            }
       }
       else
       {
           sqlfile = "";
       }
   return sqlfile;
  }
    }
}