.NET ftp文件上传和下载

文章参考来源地址：https://blog.csdn.net/wybshyy/article/details/52095542

本次对代码进行了一点扩展：将文件上传到ftp指定目录下，若目录不存在则创建目录。

调整点：在构造函数中，处理和获得可直接使用的ftpURI。

完整代码如下：

public class FtpWeb
    {
        string ftpServerIP;
        string ftpRemotePath;
        string ftpUserID;
        string ftpPassword;
        string ftpURI;

        /// <summary>
        /// 连接FTP
        /// </summary>
        /// <param name="FtpServerIP">FTP连接地址</param>
        /// <param name="FtpRemotePath">指定FTP连接成功后的当前目录, 如果不指定即默认为根目录</param>
        /// <param name="FtpUserID">用户名</param>
        /// <param name="FtpPassword">密码</param>
        public FtpWeb(string FtpServerIP, string FtpRemotePath, string FtpUserID, string FtpPassword)
        {
            ftpServerIP = FtpServerIP;
            ftpRemotePath = FtpRemotePath;
            ftpUserID = FtpUserID;
            ftpPassword = FtpPassword;
            //ftpURI = "ftp://" + ftpServerIP + "/" + ftpRemotePath + "/";
            ftpURI = CheckDirectory();
        }

        /// <summary>
        /// 上传
        /// </summary>
        /// <param name="filename"></param>
        public bool Upload(string filename, out string errorMsg)
        {
            errorMsg = "";
            FileInfo fileInf = new FileInfo(filename);
            string uri = ftpURI + fileInf.Name;
            FtpWebRequest reqFTP;

            reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));
            reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
            reqFTP.KeepAlive = false;
            reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
            reqFTP.UseBinary = true;
            reqFTP.ContentLength = fileInf.Length;
            int buffLength = 2048; //开辟2KB缓存区
            byte[] buff = new byte[buffLength];
            int contentLen;
            FileStream fs = fileInf.OpenRead();
            try
            {
                Stream strm = reqFTP.GetRequestStream();
                contentLen = fs.Read(buff, 0, buffLength);
                while (contentLen != 0)
                {
                    strm.Write(buff, 0, contentLen);
                    contentLen = fs.Read(buff, 0, buffLength);
                }
                strm.Close();
                fs.Close();
                return true;
            }
            catch (Exception ex)
            {
                errorMsg = ex.Message;
                return false;
            }
        }

        /// <summary>
        /// 下载
        /// </summary>
        /// <param name="filePath"></param>
        /// <param name="fileName"></param>
        public bool Download(string filePath, string fileName, out string errorMsg)
        {
            errorMsg = "";
            FtpWebRequest reqFTP;
            try
            {
                FileStream outputStream = new FileStream(filePath + "//" + fileName, FileMode.Create);

                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + fileName));
                reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
                reqFTP.UseBinary = true;
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                FtpWebResponse 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();
                outputStream.Close();
                response.Close();
                return true;
            }
            catch (Exception ex)
            {
                errorMsg = ex.Message;
                return false;
            }
        }
        #region 私有
        /// <summary>
        /// 获得+建立文件所在物理路径
        /// </summary>
        /// <returns></returns>
        private string CheckDirectory()
        {
            string dir = "ftp://" + ftpServerIP + "/";//根
            if (!string.IsNullOrWhiteSpace(ftpRemotePath))
            {
                var folderArr = ftpRemotePath.Split(new string[] { @"\", @"/" }, StringSplitOptions.RemoveEmptyEntries);
                if (folderArr != null && folderArr.Length > 0)
                {
                    foreach (var folder in folderArr)
                    {
                        dir = dir + folder + "/";
                        MakeDir(dir);
                    }
                }
            }
            return dir;
        }
        /// <summary>
        /// 创建目录
        /// </summary>
        /// <param name="errorMsg"></param>
        /// <returns></returns>
        private string MakeDir(string dir)
        {
            string errorMsg = "";
            FtpWebRequest reqFTP;
            try
            {
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(dir));
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                reqFTP.Method = WebRequestMethods.Ftp.MakeDirectory;
                reqFTP.KeepAlive = false;
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                response.Close();
            }
            catch (Exception ex)
            {
                errorMsg = "创建文件失败，原因: " + ex.Message;
            }
            return errorMsg;
        }
        #endregion
    }