上传图片，并生成缩略图（指定大小）

 1        /**//// <summary>
 2        /// 上传图片
 3        /// </summary>
 4        /// <param name="sender"></param>  
 5        /// <param name="e"></param>
 6        /// <returns>操作结果</returns>
 7        private bool ImageUpload(int nWidth,int nHeight)
 8        {
 9            System.Web.HttpFileCollection files = Request.Files;
10            System.Web.HttpPostedFile pf = files[0];
11            string sOldPath = pf.FileName.ToString();
12            int i = sOldPath.LastIndexOf("\\");
13            string sOldName = sOldPath.Substring(i+1,sOldPath.Length-i-1);
14            //"L"代表大图 && "S"代表缩略图
15            string sTimeNo = System.DateTime.Now.ToString("yyMMddHHmmss");
16            string sNewNameL = "L"+sTimeNo+"_"+sOldName;
17            string sNewNameS = sNewNameL.Replace("L"+sTimeNo,"S"+sTimeNo);
18            string sNewPathL = Server.MapPath("../images/uploadfiles/")+sNewNameL;
19            string sNewPathS = Server.MapPath("../images/uploadfiles/")+sNewNameS;
20            if(System.IO.File.Exists(sNewPathL)||System.IO.File.Exists(sNewPathS))
21            {
22                Page.RegisterStartupScript("FailToUpload","<script>alert('文件名已存在！');</script>");
23                return false;
24            }
25            else
26            {
27                pf.SaveAs(sNewPathL);//保存原图
28                string strContentType = pf.ContentType.ToString();
29                if(strContentType.IndexOf("image/")<0)
30                {
31                    Page.RegisterStartupScript("KeyEro","<script>alert('无效的图片格式！');</script>");
32                    return false;
33                }
34                else
35                {
36                    this.GetThumbNail(sOldPath,strContentType,sNewPathS,nWidth, nHeight);
37                    this.Image1.ImageUrl = sNewPathS;
38                    return true;
39                }
40            }
41        }
42        /**//// <summary>
43        /// 生成缩略图
44        /// </summary>
45        /// <param name="FileName">待上传文件的完全限定名</param>
46        /// <param name="strContentType">待上传文件的内容类型</param>
47        /// <param name="path">路径</param>
48        /// <param name="nWidth">宽</param>
49        /// <param name="nHeight">高</param>
50        private void GetThumbNail(string FileName,string strContentType,string path,int nWidth,int nHeight)
51        {
52            System.Drawing.Image oImage;
53            oImage = System.Drawing.Image.FromFile(FileName);
54            oImage = oImage.GetThumbnailImage(nWidth,nHeight,null,IntPtr.Zero);
55            //            MemoryStream ms = new MemoryStream();
56            //            Response.ContentType = strContentType;
57            //            oImage.Save(ms,strContentType);
58            oImage.Save(path,this.GetContenType(strContentType));
59            //            ms.WriteTo(Response.OutputStream);
60        }
61        /**//// <summary>
62        /// 获取保存文件的格式
63        /// </summary>
64        /// <param name="strContentType">待上传文件的内容类型</param>
65        /// <returns>文件格式</returns>
66        private System.Drawing.Imaging.ImageFormat GetContenType(string strContentType)
67        {
68            //只写少数几种格式
69            if(strContentType.ToString().ToLower()== "image/bmp")
70                return System.Drawing.Imaging.ImageFormat.Bmp;
71            else if(strContentType.ToString().ToLower()== "image/gif")
72                return System.Drawing.Imaging.ImageFormat.Gif;
73            else
74            return System.Drawing.Imaging.ImageFormat.Jpeg;
75        }