/// <summary>
         /// 上传文件
         /// </summary>
         /// <param name="fileinfo">需要上传的文件</param>
         /// <param name="targetDir">目标路径</param>
         /// <param name="hostname">ftp地址</param>
         /// <param name="username">ftp用户名</param>
         /// <param name="password">ftp密码</param>
         public static void UploadFile(FileInfo fileinfo, string targetDir, string hostname, string username, string password)
         {
             //1. check target
             string target;
             if (targetDir.Trim() == "")
             {
                 return;
             }
             target = Guid.NewGuid().ToString();  //使用临时文件名
 
 
             string URI = "FTP://" + hostname + "/" + targetDir + "/" + target;
             ///WebClient webcl = new WebClient();
             System.Net.FtpWebRequest ftp = GetRequest(URI, username, password);
 
             //设置FTP命令 设置所要执行的FTP命令，
             //ftp.Method = System.Net.WebRequestMethods.Ftp.ListDirectoryDetails;//假设此处为显示指定路径下的文件列表
             ftp.Method = System.Net.WebRequestMethods.Ftp.UploadFile;
             //指定文件传输的数据类型
             ftp.UseBinary = true;
             ftp.UsePassive = true;
 
             //告诉ftp文件大小
             ftp.ContentLength = fileinfo.Length;
             //缓冲大小设置为2KB
             const int BufferSize = 2048;
             byte[] content = new byte[BufferSize - 1 + 1];
             int dataRead;
 
             //打开一个文件流 (System.IO.FileStream) 去读上传的文件
             using (FileStream fs = fileinfo.OpenRead())
             {
                 try
                 {
                     //把上传的文件写入流
                     using (Stream rs = ftp.GetRequestStream())
                     {
                         do
                         {
                             //每次读文件流的2KB
                             dataRead = fs.Read(content, 0, BufferSize);
                             rs.Write(content, 0, dataRead);
                         } while (!(dataRead < BufferSize));
                         rs.Close();
                     }
 
                 }
                 catch (Exception ex) { }
                 finally
                 {
                     fs.Close();
                 }
 
             }
 
             ftp = null;
             //设置FTP命令
             ftp = GetRequest(URI, username, password);
             ftp.Method = System.Net.WebRequestMethods.Ftp.Rename; //改名
             ftp.RenameTo = fileinfo.Name;
             try
             {
                 ftp.GetResponse();
             }
             catch (Exception ex)
             {
                 ftp = GetRequest(URI, username, password);
                 ftp.Method = System.Net.WebRequestMethods.Ftp.DeleteFile; //删除
                 ftp.GetResponse();
                 throw ex;
             }
             finally
             {
                 //fileinfo.Delete();
             }
 
             // 可以记录一个日志  "上传" + fileinfo.FullName + "上传到" + "FTP://" + hostname + "/" + targetDir + "/" + fileinfo.Name + "成功." );
             ftp = null;
 
             #region
             /*****
              *FtpWebResponse
              * ****/
             //FtpWebResponse ftpWebResponse = (FtpWebResponse)ftp.GetResponse();
             #endregion
         }
 
         private static FtpWebRequest GetRequest(string URI, string username, string password)
         {
             //根据服务器信息FtpWebRequest创建类的对象
             FtpWebRequest result = (FtpWebRequest)FtpWebRequest.Create(URI);
             //提供身份验证信息
             result.Credentials = new System.Net.NetworkCredential(username, password);
             //设置请求完成之后是否保持到FTP服务器的控制连接，默认值为true
             result.KeepAlive = false;
             return result;