if(File1.PostedFile!=null)
            {
                if(File1.PostedFile.FileName.Length - File1.PostedFile.FileName.Replace(".","").Length>1)
                {
                    System.Web.HttpContext.Current.Response.Write("<script>alert('你的文件有多扩展名!');</script>");
                    return;
                }
                if(File1.PostedFile.ContentLength>1024*1024*5)
                {
                    System.Web.HttpContext.Current.Response.Write("<script>alert('你的文件大于5M了，请缩小图片大小!');</script>");
                    return;
                }
                string filename = string.Empty;
                string filename2 = File1.PostedFile.FileName;
                
                filename2 = filename2.Substring(filename2.LastIndexOf('.'));
                if(filename2!=".jpg" && filename2!=".gif")
                {
                    System.Web.HttpContext.Current.Response.Write("<script>alert('只允许上传图片文件.gif,.jpg文件!!');</script>");
                    return;
                }
                char[] namechar = DateTime.Now.ToString().ToCharArray();
                for (int i = 0; i < namechar.Length; i++)
                {
                    if (namechar[i] != '-' && namechar[i] != ':' && namechar[i] != ' ')
                        filename += namechar[i].ToString();
                }
                filename += new Random().Next(100, 999).ToString();
                filename += filename2;
                string filepath = System.Web.HttpContext.Current.Request.PhysicalApplicationPath + "/" + uploadType;
                File1.PostedFile.SaveAs(filepath + "/" + filename);
                Image1.ImageUrl = "/" + uploadType + "/" + filename;
            }

------解决方案--------------------
图片上传如楼上所未..

视频也可以按那样的来...

不过,往往视频都很大..用这个方法不行吧...找找超级上传组件试试

------解决方案--------------------

if(File1.PostedFile!=null)
           {
               if(File1.PostedFile.FileName.Length - File1.PostedFile.FileName.Replace(".","").Length>1)
               {
                   System.Web.HttpContext.Current.Response.Write("<script>alert('你的文件有多扩展名!');</script>");
                   return;
               }
               if(File1.PostedFile.ContentLength>1024*1024*5)
               {
                   System.Web.HttpContext.Current.Response.Write("<script>alert('你的文件大于5M了，请缩小图片大小!');</script>");
                   return;
               }
               string filename = string.Empty;
               string filename2 = File1.PostedFile.FileName;
              
               filename2 = filename2.Substring(filename2.LastIndexOf('.'));
               if(filename2!=".jpg" && filename2!=".gif")
               {
                   System.Web.HttpContext.Current.Response.Write("<script>alert('只允许上传图片文件.gif,.jpg文件!!');</script>");
                   return;
               }
               char[] namechar = DateTime.Now.ToString().ToCharArray();
               for (int i = 0; i < namechar.Length; i++)
               {
                   if (namechar[i] != '-' && namechar[i] != ':' && namechar[i] != ' ')
                       filename += namechar[i].ToString();
               }
               filename += new Random().Ne