如果自己单枪匹马写一个连接ftp服务器代码那是相当恐怖的（socket通信），有一个评价较高的dll库可以供我们使用。
那就是System.Net.FtpClient，链接地址：https://netftp.codeplex.com
然后下载该资源，我们就可以使用它的函数了。这里介绍一下如何使用System.Net.FtpClient链接ftp服务器并下载服务器中的文件。
千万别忘了添加引用——导入System.Net.FtpClient.dll.
还有就是 using System.Net.FtpClient;
using System.Net;
using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Net;using System.Net.FtpClient;using System.Text;using System.Threading.Tasks;using System.IO;namespace FTP_Client{ public class FTPConnection { public FTPConnection() { } /// <summary> /// 连接FTP服务器函数 /// </summary> /// <param name="strServer">服务器IP</param> /// <param name="strUser">用户名</param> /// <param name="strPassword">密码</param> public bool FTPIsConnected(string strServer, string strUser, string strPassword) { using (FtpClient ftp = new FtpClient()) { ftp.Host = strServer; ftp.Credentials = new NetworkCredential(strUser, strPassword); ftp.Connect(); return ftp.IsConnected; } } /// <summary> /// FTP下载文件 /// </summary> /// <param name="strServer">服务器IP</param> /// <param name="strUser">用户名</param> /// <param name="strPassword">密码</param> /// <param name="Serverpath">服务器路径，例子："/Serverpath/"</param> /// <param name="localpath">本地保存路径</param> /// <param name="filetype">所下载的文件类型,例子：".rte"</param> public bool FTPIsdownload(string strServer, string strUser, string strPassword,string Serverpath, string localpath, string filetype) { FtpClient ftp = new FtpClient(); ftp.Host = strServer; ftp.Credentials = new NetworkCredential(strUser, strPassword); ftp.Connect(); string path = Serverpath; string destinationDirectory = localpath; List<string> documentname = new List<string>(); bool DownloadStatus = false; if (Directory.Exists(destinationDirectory)) { #region 从FTP服务器下载文件 foreach (var ftpListItem in ftp.GetListing(path, FtpListOption.Modify | FtpListOption.Size) .Where(ftpListItem => string.Equals(Path.GetExtension(ftpListItem.Name), filetype))) { string destinationPath = string.Format(@"{0}\{1}", destinationDirectory, ftpListItem.Name); using (Stream ftpStream = ftp.OpenRead(ftpListItem.FullName)) using (FileStream fileStream = File.Create(destinationPath, (int)ftpStream.Length)) { var buffer = new byte[200 * 1024]; int count; while ((count = ftpStream.Read(buffer, 0, buffer.Length)) > 0) { fileStream.Write(buffer, 0, count); } } documentname.Add(ftpListItem.Name); } #endregion #region 验证本地是否有该文件 string[] files = Directory.GetFiles(localpath, "*"+filetype); int filenumber = 0; foreach(string strfilename in files) { foreach(string strrecievefile in documentname) { if (strrecievefile == Path.GetFileName(strfilename)) { filenumber++; break; } } } if(filenumber==documentname.Count) { DownloadStatus = true; } #endregion } return DownloadStatus; } }}
原标题：C# System.Net.FtpClient库连接ftp服务器
关键词：.NET
我知道了 