c# 剖析FTP，实现文件上传、下载和删除

1.把本地指定文件上传到FTP文件服务器

        private  string ftpServer; //FTP的服务器地址
        private  string uNAME;  //FTP服务器的用户名
        private  string pwd;    //FTP服务器的密码
        private string ip; //FTP服务器IP
        private string port; //FTP服务器端口
        /// <summary>
        /// FTP文件上传
        /// </summary>
        /// <param name="ftpPath">要上传到FTP那个目录 /MES系统一课备份/2023年/7月/晶创-哥瑞利MES系统</param>
        /// <param name="fileName">要文件名称 20230717_PDAService.txt</param>
        /// <param name="localPath">本地文件路径+文件名称 E:\Logs\PDAService\PDAService\20230717_PDAService.txt</param>
        /// <param name="timeOut">上传失效时间</param>
        /// <returns></returns>
        public Boolean FtpUpload(string ftpPath,string fileName, string localPath, int timeOut)
        {
            //检查目录是否存在，不存在创建  
            string[] paths = ftpPath.Split("/".ToCharArray());
            string prePath = "";
            for (int i = 0; i < paths.Length - 1; i++)
            {
                if (!string.IsNullOrEmpty(paths[i])) 
                {
                    prePath += paths[i] + "/";
                    FtpCheckDirectoryExist(prePath, uNAME, pwd);
                }                
            }

            FileInfo fi = new FileInfo(localPath);
            var uri = ftpServer + ftpPath+"/"+fileName;//要上传的文件路径，含要上传名称 注：此处必须要加入文件名
            FtpWebRequest req = (FtpWebRequest)WebRequest.Create(new Uri(uri));
            req.Credentials = new NetworkCredential(uNAME, pwd);
            req.KeepAlive = true;
            req.Method = WebRequestMethods.Ftp.UploadFile;
            req.UsePassive = false;
            req.UseBinary = true;
            req.ContentLength = fi.Length;
            req.Timeout = timeOut;
            req.ServicePoint.Expect100Continue = false;
            FileStream fs = fi.OpenRead();
            try
            {
                Stream stream = req.GetRequestStream();
                int BufferLength = 2048; //2K     
                byte[] b = new byte[BufferLength];
                int i;
                while ((i = fs.Read(b, 0, BufferLength)) > 0)
                {
                    stream.Write(b, 0, i);
                }
                stream.Close();
                stream.Dispose();
            }
            catch
            {
                return false;
            }
            finally
            {
                fs.Close();
                req.Abort();
            }
            return true;
        }
          //判断文件的目录是否存,不存则创建  
        private static void FtpCheckDirectoryExist(string destFilePath, string ftpUserID, string ftpPassword)
        {
            string fullDir = FtpParseDirectory(destFilePath);
            try
            {
                if (fullDir != "")
                {
                    FtpMakeDir(fullDir, ftpUserID, ftpPassword);
                }
            }
            catch (Exception)
            { }
        }
         private static string FtpParseDirectory(string destFilePath)
        {
            if (destFilePath.LastIndexOf("/") > 0)
            {
                return destFilePath.Substring(0, destFilePath.LastIndexOf("/"));
            }
            if (destFilePath.LastIndexOf(@"\") > 0)
            {
                return destFilePath.Substring(0, destFilePath.LastIndexOf(@"\"));
            }
            return "";
        }
        //创建目录  
        public static Boolean FtpMakeDir(string localFile, string ftpUserID, string ftpPassword)
        {
            FtpWebRequest req = (FtpWebRequest)WebRequest.Create(localFile);
            req.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
            req.Method = WebRequestMethods.Ftp.MakeDirectory;
            try
            {
                FtpWebResponse response = (FtpWebResponse)req.GetResponse();
                response.Close();
            }
            catch (Exception)
            {
                req.Abort();
                return false;
            }
            req.Abort();
            return true;
        }

2.从FTP服务器下载文件到本地指定文件夹

        /// <summary>
        /// FTP下载
        /// </summary>
        /// <param name="ftpPath">FTP下载路径（不包含FTP的服务器地址）</param>
        /// <param name="folderPath">本地路径（下载文件存放路径）</param>
        /// <param name="fileName">下载文件名</param>
        /// <param name="timeOut"></param>
        public void FtpDownload(string ftpPath, string folderPath, string fileName, int timeOut)
        {
            FtpWebRequest reqFTP;
            FileStream outputStream = new FileStream(folderPath + fileName, FileMode.Create);
            var uri = ftpServer + ftpPath + "/" + fileName;
            reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));
            reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
            reqFTP.KeepAlive = true;
            reqFTP.UseBinary = true;
            reqFTP.Credentials = new NetworkCredential(uNAME, pwd);
            reqFTP.UsePassive = false;
            reqFTP.Timeout = timeOut;
            FtpWebResponse response = null;
            try
            {
                response = (FtpWebResponse)reqFTP.GetResponse();
                Stream ftpStream = response.GetResponseStream();
                long cl = response.ContentLength;
                int bufferSize = 2048;
                int readCount;
                byte[] buffer = new byte[bufferSize];
                readCount = ftpStream.Read(buffer, 0, bufferSize);
                while (readCount > 0)
                {
                    outputStream.Write(buffer, 0, readCount);
                    readCount = ftpStream.Read(buffer, 0, bufferSize);
                }
                ftpStream.Close();

            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                outputStream.Close();
                if (response != null)
                {
                    response.Close();
                }
            }
        }

3.删除FTP服务器指定的文件

 /// <summary>
        /// 删除FTP指定文件信息
        /// </summary>
        /// <param name="filePath">FTP服务目录</param>
        /// <param name="fileName">删除的文件名称</param>
        public void DeleteFile(string filePath,string fileName)
        {
            try
            {
                FtpWebRequest reqFTP;
                var uri = ftpServer + filePath + "/" + fileName;
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));

                reqFTP.Credentials = new NetworkCredential(uNAME, pwd);
                reqFTP.KeepAlive = false;
                reqFTP.Method = WebRequestMethods.Ftp.DeleteFile;

                string result = String.Empty;
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                long size = response.ContentLength;
                Stream datastream = response.GetResponseStream();
                StreamReader sr = new StreamReader(datastream);
                result = sr.ReadToEnd();
                sr.Close();
                datastream.Close();
                response.Close();
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }