public static bool DeleteFileOnServer(Uri serverUri)
        {
            // The serverUri parameter should use the ftp:// scheme. 
            // It contains the name of the server file that is to be deleted. 
            // Example: ftp://contoso.com/someFile.txt. 
            // 
            if (serverUri.Scheme != Uri.UriSchemeFtp)
            {
                return false;
            }
            // Get the object used to communicate with the server. 
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(serverUri);
            request.Method = WebRequestMethods.Ftp.DeleteFile;
            FtpWebResponse response = (FtpWebResponse)request.GetResponse();
            Console.WriteLine("Delete status: {0}", response.StatusDescription);
            response.Close();
            return true;
        }

class FtpClient
    {
        string userName;
        string passWord;

        byte[] buffer = new byte[1024 * 20];

        public FtpClient(string userName, string passWord)
        {
            this.userName = userName;
            this.passWord = passWord;
        }

        /**//// <summary>
        /// 创建ftp请求信息
        /// </summary>
        /// <param name="url">目标url地址</param>
        /// <param name="useBinary">是否使用二进制传输</param>
        private FtpWebRequest GetRequest(string url, bool useBinary)
        {
            FtpWebRequest ftpRequest = (FtpWebRequest)WebRequest.Create(url);
            ftpRequest.Credentials = new NetworkCredential(userName, passWord);
            ftpRequest.UseBinary = useBinary;
            ftpRequest.KeepAlive = true;
            return ftpRequest;
        }

        private FtpWebRequest GetRequest(string url)
        {
            return GetRequest(url, false);
        }

        string GetStreamText(Stream stream)
        {
            StreamReader reader = new StreamReader(stream, Encoding.Default);
            string text = reader.ReadToEnd();
            reader.Close();
            return text;
        }

        //将orgStream中的内容拷贝到desStream中
        void WriteStream(Stream orgStream, Stream desStream)
        {
            int num;
            while ((num = orgStream.Read(buffer, 0, buffer.Length)) > 0)
            {
                desStream.Write(buffer, 0, num);
            }
            orgStream.Close();
            desStream.Close();
        }

        /**//// <summary>
        /// 列出ftp目录所包含的文件信息
        /// </summary>
        /// <param name="remoteDir">远程文件夹</param>
        /// <returns>文件详细信息</returns>
        public string ListFiles(string remoteDir)
        {
            FtpWebRequest request = GetRequest(remoteDir, false);
            request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
            return GetStreamText(request.GetResponse().GetResponseStream());
        }

        /**//// <summary>
        /// 下载文件
        /// </summary>
        /// <param name="localFile">本地文件路径</param>
        /// <param name="remoteFile">远程文件路径</param>
        /// <param name="useBinary">是否采用二进制方式</param>
        public void DownloadFile(string localFile, string remoteFile, bool useBinary)
        {
            FtpWebRequest request = GetRequest(remoteFile, useBinary);
            request.Method = WebRequestMethods.Ftp.DownloadFile;

            WriteStream(request.GetResponse().GetResponseStream(), File.Create(localFile));
        }

        /**//// <summary>
        /// 上传文件
        /// </summary>
        /// <param name="localFile">本地文件路径</param>
        /// <param name="remoteFile">远程文件路径</param>
        /// <param name="useBinary">是否采用二进制方式</param>
        public void UploadFile(string localFile, string remoteFile, bool useBinary)
        {
            FileInfo fi = new FileInfo(localFile);
            FtpWebRequest request = GetRequest(remoteFile, useBinary);
            request.Method = WebRequestMethods.Ftp.UploadFile;
            request.ContentLength = fi.Length;

            WriteStream(fi.OpenRead(),request.GetRequestStream());
            request.GetResponse();
        }

        //删除文件
        public void DeleteFile(string remoteFile)
        {
            FtpWebRequest request = GetRequest(remoteFile);
            request.Method = WebRequestMethods.Ftp.DeleteFile;

            FtpWebResponse resp = request.GetResponse() as FtpWebResponse;
        }
    }