using System; 
using System.Collections.Generic; 
using System.Net; 
using System.IO; 
using System.Windows.Forms; 
using System.Text; 
 
namespace FTPDownLoad 
{ 
    class FtpFileInfo 
    { 
        public string FileName; 
        public DateTime ModifyDateTime; 
        public bool IsDirectory; 
    } 
    class FtpHelper 
    { 
        private string ftpServer; 
        private string userName; 
        private string password; 
        FtpWebRequest ftpRequest = null; 
        private string errMsg; 
        public string ErrMsg 
        { 
            get { return errMsg; } 
            set { errMsg = value; } 
        } 
        public bool IsAnonymous 
        { 
            get 
            { 
                return !(userName != null && userName.Trim() != String.Empty 
                        && password != null && password.Trim() != string.Empty); 
            } 
        } 
 
        public FtpHelper(string ftpServer, string userName, string password) 
        { 
            this.ftpServer = ftpServer; 
            this.userName = userName; 
            this.password = password; 
        } 
 
        /**/ 
        /// <summary> 
        /// 取得服务器端的文件链表 
        /// </summary> 
        /// <param name="serverPath"></param> 
        /// <returns></returns> 
        public List<FtpFileInfo> GetFilesList(string serverPath) 
        { 
            List<FtpFileInfo> fileInfoList = new List<FtpFileInfo>(); 
            Uri uri = new Uri("ftp://" + ftpServer + serverPath); 
            StreamReader sr = null; 
            try 
            { 
                ftpRequest = (FtpWebRequest)FtpWebRequest.Create(uri); 
                if (ftpRequest == null) throw new Exception("无法打开ftp服务器连接"); 
                ftpRequest.Method = WebRequestMethods.Ftp.ListDirectoryDetails;   //列表    
                if (!IsAnonymous) 
                { 
                    ftpRequest.Credentials = new NetworkCredential(userName, password); 
                } 
 
                sr = new StreamReader(ftpRequest.GetResponse().GetResponseStream()); 
                while (!sr.EndOfStream)//读取列表    
                { 
                    //System.Diagnostics.Debug.WriteLine(sr.ReadLine()); 
                    char[] splitChar = { ' ' }; 
                    string[] tmpArray = sr.ReadLine().Split(splitChar, StringSplitOptions.RemoveEmptyEntries); 
                    if (tmpArray.Length != 9) 
                    { 
                        continue; 
                    } 
                    FtpFileInfo ffi = new FtpFileInfo(); 
                    ffi.IsDirectory = tmpArray[0].StartsWith("d"); 
                    if (!ffi.IsDirectory) 
                    { 
                        ffi.FileName = tmpArray[8]; 
                        fileInfoList.Add(ffi); 
                    } 
                    else 
                    { 
                        continue; 
                    } 
                } 
            } 
            catch (Exception ex) 
            { 
                //TODO: 异常处理. 
                throw ex; 
            } 
            finally 
            { 
                if (sr != null) sr.Close(); 
            } 
 
            foreach (FtpFileInfo ffi in fileInfoList) 
            { 
                ffi.ModifyDateTime = this.GetFileModifyTime(serverPath, ffi.FileName); 
            } 
            return fileInfoList; 
        } 
        /**/ 
        /// <summary> 
        /// Download 
        /// </summary> 
        /// <param name="serverPath"></param> 
        /// <param name="serverFileName"></param> 
        /// <param name="localPath"></param> 
        /// <param name="localFileName"></param> 
        /// <returns></returns> 
        public bool Download(string serverPath, string serverFileName, string localPath, string localFileName) 
        { 
            if (!Directory.Exists(localPath)) 
            { 
                //TODO: 创建文件夹 
                errMsg = "本地路径不存在: " + localPath; 
                return false; 
            } 
            FileStream outputStream = null; 
            Stream ftpStream = null; 
            try 
            { 
                outputStream = new FileStream(localPath + "\\" + localFileName, FileMode.Create); 
                if (outputStream == null) 
                { 
                    errMsg = "无法创建本地文件"; 
                    return false; 
                } 
                ftpRequest = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpServer + serverPath + "/" + serverFileName)); 
                if (ftpRequest == null) 
                { 
                    errMsg = "无法连接服务器"; 
                    return false; 
                } 
                ftpRequest.Method = WebRequestMethods.Ftp.DownloadFile; 
                ftpRequest.UseBinary = true; 
                //用户验证 
                if (!IsAnonymous) 
                { 
                    ftpRequest.Credentials = new NetworkCredential(userName, password); 
                } 
                ftpStream = ftpRequest.GetResponse().GetResponseStream(); 
                int bufferSize = 2048; 
                int readCount; 
                byte[] buffer = new byte[bufferSize]; 
 
                while ((readCount = ftpStream.Read(buffer, 0, bufferSize)) > 0) 
                { 
                    outputStream.Write(buffer, 0, readCount); 
                } 
            } 
            catch (Exception ex) 
            { 
                errMsg = ex.ToString(); 
                return false; 
            } 
            finally 
            { 
                if (ftpStream != null) ftpStream.Close(); 
                if (outputStream != null) outputStream.Close(); 
            } 
            FileInfo fi = new FileInfo(localPath + "\\" + localFileName); 
            fi.LastWriteTime = GetFileModifyTime(serverPath, serverFileName); 
            return true; 
        } 
 
        public void DownLoadDirectory(String ServerPath, String LocalPath) 
        { 
            //取服务器端要下载的目录里的文件列表 
            List<FtpFileInfo> serFileList = GetFilesList(ServerPath); 
            foreach (FtpFileInfo ftpFile in serFileList) 
            { 
                if (ftpFile.IsDirectory) continue; 
                DateTime modifyTime = ftpFile.ModifyDateTime; 
                string localFileName = modifyTime.ToString("yyyyMMddHHmmss") + "_" + ftpFile.FileName; 
 
                // 如果本地不存在该文件,则说明该文件是比较新的文件,需要下载. 
                if (!File.Exists(LocalPath + "\\" + localFileName)) 
                { 
                    if (!Download(ServerPath, ftpFile.FileName, LocalPath, localFileName)) 
                    { 
                        MessageBox.Show("下载文件出错!\r\n错误原因: " + ErrMsg); 
                    } 
                } 
            } 
        } 
 
        public DateTime GetFileModifyTime(string serverPath, string fileName) 
        { 
            Uri uri = new Uri("ftp://" + ftpServer + serverPath + "/" + fileName); 
            DateTime dt = DateTime.Now; 
            try 
            { 
                ftpRequest = (FtpWebRequest)WebRequest.Create(uri); 
                if (!IsAnonymous) 
                { 
                    ftpRequest.Credentials = new NetworkCredential(userName, password); 
                } 
                ftpRequest.Method = WebRequestMethods.Ftp.GetDateTimestamp; 
                ftpRequest.UseBinary = true; 
                ftpRequest.UsePassive = false; 
                dt = ((FtpWebResponse)ftpRequest.GetResponse()).LastModified; 
            } 
            catch (Exception ex) 
            { 
                //TODO: 错误处理 
                throw ex; 
            } 
            return dt; 
        } 
    } 
}