将用户上传的附件（文件、图片等）通过FTP方式传送到另外一台服务器上，从而缓解服务器压力
1、相关的文章如下：
Discuz!NT中远程附件的功能实现[FTP协议]
http://www.cnblogs.com/daizhj/archive/2008/07/28/1254648.html
2、以下代码使用.net FtpWebRequest 实现FTP的常用功能， 代码已经调试通过， 可复制直接使用。 经测试使用此种方式实现的FTP操作与直接使用命令的方式操作FTP要稳定许多。 有设计不好的地方请指正。需要.net2.0以上。
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Net;
using System.Windows.Forms;
using System.Globalization; namespace FtpTest1
{ 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 + "/";
} /// <summary>
/// 上传
/// </summary>
/// <param name="filename"></param>
public void Upload(string filename)
{
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;
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();
}
catch (Exception ex)
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "Upload Error --> " + ex.Message);
}
} /// <summary>
/// 下载
/// </summary>
/// <param name="filePath"></param>
/// <param name="fileName"></param>
public void Download(string filePath, string fileName)
{
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();
}
catch (Exception ex)
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "Download Error --> " + ex.Message);
}
} /// <summary>
/// 删除文件
/// </summary>
/// <param name="fileName"></param>
public void Delete(string fileName)
{
try
{
string uri = ftpURI + fileName;
FtpWebRequest reqFTP;
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri)); reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
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)
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "Delete Error --> " + ex.Message + " 文件名:" + fileName);
}
} /// <summary>
/// 获取当前目录下明细(包含文件和文件夹)
/// </summary>
/// <returns></returns>
public string[] GetFilesDetailList()
{
string[] downloadFiles;
try
{
StringBuilder result = new StringBuilder();
FtpWebRequest ftp;
ftp = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI));
ftp.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
ftp.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
WebResponse response = ftp.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream());
string line = reader.ReadLine();
line = reader.ReadLine();
line = reader.ReadLine();
while (line != null)
{
result.Append(line);
result.Append("\n");
result.Remove(result.ToString().LastIndexOf("\n"), 1);
reader.Close();
response.Close();
return result.ToString().Split('\n');
}
catch (Exception ex)
{
downloadFiles = null;
Insert_Standard_ErrorLog.Insert("FtpWeb", "GetFilesDetailList Error --> " + ex.Message);
return downloadFiles;
}
} /// <summary>
/// 获取当前目录下文件列表(仅文件)
/// </summary>
/// <returns></returns>
public string[] GetFileList(string mask)
{
string[] downloadFiles;
StringBuilder result = new StringBuilder();
FtpWebRequest reqFTP;
try
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI));
reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
WebResponse response = reqFTP.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream()); string line = reader.ReadLine();
while (line != null)
{
if (mask.Trim() != string.Empty && mask.Trim() != "*.*")
{
string mask_ = mask.Substring(0, mask.IndexOf("*"));
if (line.Substring(0, mask_.Length) == mask_)
{
result.Append(line);
result.Append("\n");
}
}
else
{
result.Append(line);
result.Append("\n");
}
line = reader.ReadLine();
}
result.Remove(result.ToString().LastIndexOf('\n'), 1);
reader.Close();
response.Close();
return result.ToString().Split('\n');
}
catch (Exception ex)
{
downloadFiles = null;
if (ex.Message.Trim() != "远程服务器返回错误: (550) 文件不可用(例如，未找到文件，无法访问文件)。")
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "GetFileList Error --> " + ex.Message.ToString());
}
return downloadFiles;
}
} /// <summary>
/// 获取当前目录下所有的文件夹列表(仅文件夹)
/// </summary>
& nbsp; /// <returns></returns>
public string[] GetDirectoryList()
{
string[] drectory = GetFilesDetailList();
string m = string.Empty;
foreach (string str in drectory)
{
if (str.Trim().Substring(0, 1).ToUpper() == "D")
{
m += str.Substring(54).Trim() + "\n";
}
} char[] n = new char[]{'\n'};
return m.Split(n);
} /// <summary>
/// 判断当前目录下指定的子目录是否存在
/// </summary>
/// <param name="RemoteDirectoryName">指定的目录名</param>
public bool DirectoryExist(string RemoteDirectoryName)
{
string[] dirList = GetDirectoryList();
foreach (string str in dirList)
{
if (str.Trim() == RemoteDirectoryName.Trim())
{
return true;
}
}
return false;
} /// <summary>
/// 判断当前目录下指定的文件是否存在
/// </summary>
/// <param name="RemoteFileName">远程文件名</param>
public bool FileExist(string RemoteFileName)
{
string[] fileList = GetFileList("*.*");
foreach (string str in fileList)
{
if (str.Trim() == RemoteFileName.Trim())
{
return true;
}
}
return false;
} /// <summary>
/// 创建文件夹
/// </summary>
/// <param name="dirName"></param>
public void MakeDir(string dirName)
{
FtpWebRequest reqFTP;
try
{
// dirName = name of the directory to create.
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + dirName));
reqFTP.Method = WebRequestMethods.Ftp.MakeDirectory;
reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream(); ftpStream.Close();
response.Close();
}
catch (Exception ex)
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "MakeDir Error --> " + ex.Message);
}
} /// <summary>
/// 获取指定文件大小
/// </summary>
/// <param name="filename"></param>
/// <returns></returns>
public long GetFileSize(string filename)
{
FtpWebRequest reqFTP;
long fileSize = 0;
try
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + filename));
reqFTP.Method = WebRequestMethods.Ftp.GetFileSize; ; reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream();
fileSize = response.ContentLength; ftpStream.Close();
response.Close();
}
catch (Exception ex)
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "GetFileSize Error --> " + ex.Message);
}
return fileSize;
} /// <summary>
/// 改名
/// </summary>
/// <param name="currentFilename"></param>
/// <param name="newFilename"></param>
public void ReName(string currentFilename, string newFilename)
{
FtpWebRequest reqFTP;
try
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + currentFilename));
reqFTP.Method = WebRequestMethods.Ftp.Rename;
reqFTP.RenameTo = newFilename;
reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream(); ftpStream.Close();
response.Close();
}
catch (Exception ex)
{
Insert_Standard_ErrorLog.Insert("FtpWeb", "ReName Error --> " + ex.Message);
}
} /// <summary>
/// 移动文件
/// </summary>
/// <param name="currentFilename"></param>
/// <param name="newFilename"></param>
public void MovieFile(string currentFilename, string newDirectory)
{
ReName(currentFilename, newDirectory);
} /// <summary>
/// 切换当前目录
/// </summary>
/// <param name="DirectoryName"></param>
/// <param name="IsRoot">true 绝对路径 false 相对路径</param>
public void GotoDirectory(string DirectoryName, bool IsRoot)
{
if (IsRoot)
{
ftpRemotePath = DirectoryName;
}
else
{
ftpRemotePath += DirectoryName + "/";
}
ftpURI = "ftp://" + ftpServerIP + "/" + ftpRemotePath + "/";
} } public class Insert_Standard_ErrorLog
{
public static void Insert(string x, string y )
{ }
} }
另一个ftp操作类：http://www.cnblogs.com/MikeChen/archive/2010/06/12/1756777.html