一个FTP客户端的C#代码

using System;
using System.Net;
using System.IO;
using System.Text;
using System.Net.Sockets;

namespace zhangyuk.net.csdn.blog.ftpclient
{
 /// <summary>
 /// FTP Client
 /// </summary>
 public class FTPClient
 {
  #region 构造函数
  /// <summary>
  /// 缺省构造函数
  /// </summary>
  public FTPClient()
  {
   strRemoteHost  = "";
   strRemotePath  = "";
   strRemoteUser  = "";
   strRemotePass  = "";
   strRemotePort  = 21;
   bConnected     = false;
  }

  /// <summary>
  /// 构造函数
  /// </summary>
  /// <param></param>
  /// <param></param>
  /// <param></param>
  /// <param></param>
  /// <param></param>
  public FTPClient( string remoteHost, string remotePath, string remoteUser, string remotePass, int remotePort )
  {
   strRemoteHost  = remoteHost;
   strRemotePath  = remotePath;
   strRemoteUser  = remoteUser;
   strRemotePass  = remotePass;
   strRemotePort  = remotePort;
   Connect();
  }
  #endregion

  #region 登陆
  /// <summary>
  /// FTP服务器IP地址
  /// </summary>
  private string strRemoteHost;
  public string RemoteHost
  {
   get
   {
    return strRemoteHost;
   }
   set
   {
    strRemoteHost = value;
   }
  }
  /// <summary>
  /// FTP服务器端口
  /// </summary>
  private int strRemotePort;
  public int RemotePort
  {
   get
   {
    return strRemotePort;
   }
   set
   {
    strRemotePort = value;
   }
  }
  /// <summary>
  /// 当前服务器目录
  /// </summary>
  private string strRemotePath;
  public string RemotePath
  {
   get
   {
    return strRemotePath;
   }
   set
   {
    strRemotePath = value;
   }
  }
  /// <summary>
  /// 登录用户账号
  /// </summary>
  private string strRemoteUser;
  public string RemoteUser
  {
   set
   {
    strRemoteUser = value;
   }
  }
  /// <summary>
  /// 用户登录密码
  /// </summary>
  private string strRemotePass;
  public string RemotePass
  {
   set
   {
    strRemotePass = value;
   }
  }

  /// <summary>
  /// 是否登录
  /// </summary>
  private Boolean bConnected;
  public bool Connected
  {
   get
   {
    return bConnected;
   }
  }
  #endregion

  #region 链接
  /// <summary>
  /// 建立连接
  /// </summary>
  public void Connect()
  {
   socketControl = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
   IPEndPoint ep = new IPEndPoint(IPAddress.Parse(RemoteHost), strRemotePort);
   // 链接
   try
   {
    socketControl.Connect(ep);
   }
   catch(Exception)
   {
    throw new IOException("Couldn't connect to remote server");
   }

   // 获取应答码
   ReadReply();
   if(iReplyCode != 220)
   {
    DisConnect();
    throw new IOException(strReply.Substring(4));
   }

   // 登陆
   SendCommand("USER "+strRemoteUser);
   if( !(iReplyCode == 331 || iReplyCode == 230) )
   {
    CloseSocketConnect();//关闭连接
    throw new IOException(strReply.Substring(4));
   }
   if( iReplyCode != 230 )
   {
    SendCommand("PASS "+strRemotePass);
    if( !(iReplyCode == 230 || iReplyCode == 202) )
    {
     CloseSocketConnect();//关闭连接
     throw new IOException(strReply.Substring(4));
    }
   }
   bConnected = true;

   // 切换到目录
   ChDir(strRemotePath);
  }
   

  /// <summary>
  /// 关闭连接
  /// </summary>
  public void DisConnect()
  {
   if( socketControl != null )
   {
    SendCommand("QUIT");
   }
   CloseSocketConnect();
  }

  #endregion

  #region 传输模式

  /// <summary>
  /// 传输模式:二进制类型、ASCII类型
  /// </summary>
  public enum TransferType {Binary,ASCII};

  /// <summary>
  /// 设置传输模式
  /// </summary>
  /// <param>传输模式</param>
  public void SetTransferType(TransferType ttType)
  {
   if(ttType == TransferType.Binary)
   {
    SendCommand("TYPE I");//binary类型传输
   }
   else
   {
    SendCommand("TYPE A");//ASCII类型传输
   }
   if (iReplyCode != 200)
   {
    throw new IOException(strReply.Substring(4));
   }
   else
   {
    trType = ttType;
   }
  }

  /// <summary>
  /// 获得传输模式
  /// </summary>
  /// <returns>传输模式</returns>
  public TransferType GetTransferType()
  {
   return trType;
  }
   
  #endregion

  #region 文件操作
  /// <summary>
  /// 获得文件列表
  /// </summary>
  /// <param>文件名的匹配字符串</param>
  /// <returns></returns>
  public string[] Dir(string strMask)
  {
   // 建立链接
   if(!bConnected)
   {
    Connect();
   }

   //建立进行数据连接的socket
   Socket socketData = CreateDataSocket();
  
   //传送命令
   SendCommand("NLST " + strMask);

   //分析应答代码
   if(!(iReplyCode == 150 || iReplyCode == 125 || iReplyCode == 226))
   {
    throw new IOException(strReply.Substring(4));
   }

   //获得结果
   strMsg = "";
   while(true)
   {
    int iBytes = socketData.Receive(buffer, buffer.Length, 0);
    strMsg += ASCII.GetString(buffer, 0, iBytes);
    if(iBytes < buffer.Length)
    {
     break;
    }
   }
   char[] seperator = {'\n'};
   string[] strsFileList = strMsg.Split(seperator);
   socketData.Close();//数据socket关闭时也会有返回码
   if(iReplyCode != 226)
   {
    ReadReply();
    if(iReplyCode != 226)
    {
     throw new IOException(strReply.Substring(4));
    }
   }
   return strsFileList;
  }
   

  /// <summary>
  /// 获取文件大小
  /// </summary>
  /// <param>文件名</param>
  /// <returns>文件大小</returns>
  private long GetFileSize(string strFileName)
  {
   if(!bConnected)
   {
    Connect();
   }
   SendCommand("SIZE " + Path.GetFileName(strFileName));
   long lSize=0;
   if(iReplyCode == 213)
   {
    lSize = Int64.Parse(strReply.Substring(4));
   }
   else
   {
    throw new IOException(strReply.Substring(4));
   }
   return lSize;
  }

  /// <summary>
  /// 删除
  /// </summary>
  /// <param>待删除文件名</param>
  public void Delete(string strFileName)
  {
   if(!bConnected)
   {
    Connect();
   }
   SendCommand("DELE "+strFileName);
   if(iReplyCode != 250)
   {
    throw new IOException(strReply.Substring(4));
   }
  }
   

  /// <summary>
  /// 重命名(如果新文件名与已有文件重名,将覆盖已有文件)
  /// </summary>
  /// <param>旧文件名</param>
  /// <param>新文件名</param>
  public void Rename(string strOldFileName,string strNewFileName)
  {
   if(!bConnected)
   {
    Connect();
   }
   SendCommand("RNFR "+strOldFileName);
   if(iReplyCode != 350)
   {
    throw new IOException(strReply.Substring(4));
   }
   //  如果新文件名与原有文件重名,将覆盖原有文件
   SendCommand("RNTO "+strNewFileName);
   if(iReplyCode != 250)
   {
    throw new IOException(strReply.Substring(4));
   }
  }
  #endregion

  #region 上传和下载
  /// <summary>
  /// 下载一批文件
  /// </summary>
  /// <param>文件名的匹配字符串</param>
  /// <param>本地目录(不得以\结束)</param>
  public void Get(string strFileNameMask,string strFolder)
  {
   if(!bConnected)
   {
    Connect();
   }
   string[] strFiles = Dir(strFileNameMask);
   foreach(string strFile in strFiles)
   {
    if(!strFile.Equals(""))//一般来说strFiles的最后一个元素可能是空字符串
    {
     Get(strFile,strFolder,strFile);
    }
   }
  }
   

  /// <summary>
  /// 下载一个文件
  /// </summary>
  /// <param>要下载的文件名</param>
  /// <param>本地目录(不得以\结束)</param>
  /// <param>保存在本地时的文件名</param>
  public void Get(string strRemoteFileName,string strFolder,string strLocalFileName)
  {
   if(!bConnected)
   {
    Connect();
   }
   SetTransferType(TransferType.Binary);
   if (strLocalFileName.Equals(""))
   {
    strLocalFileName = strRemoteFileName;
   }
   if(!File.Exists(strLocalFileName))
   {
    Stream st = File.Create(strLocalFileName);
    st.Close();
   }
   FileStream output = new
   FileStream(strFolder + "\\" + strLocalFileName,FileMode.Create);
   Socket socketData = CreateDataSocket();
   SendCommand("RETR " + strRemoteFileName);
   if(!(iReplyCode == 150 || iReplyCode == 125
   || iReplyCode == 226 || iReplyCode == 250))
   {
    throw new IOException(strReply.Substring(4));
   }
   while(true)
   {
    int iBytes = socketData.Receive(buffer, buffer.Length, 0);
    output.Write(buffer,0,iBytes);
    if(iBytes <= 0)
    {
     break;
    }
   }
   output.Close();
   if (socketData.Connected)
   {
    socketData.Close();
   }
   if(!(iReplyCode == 226 || iReplyCode == 250))
   {
    ReadReply();
    if(!(iReplyCode == 226 || iReplyCode == 250))
    {
     throw new IOException(strReply.Substring(4));
    }
   }
  }
   

  /// <summary>
  /// 上传一批文件
  /// </summary>
  /// <param>本地目录(不得以\结束)</param>
  /// <param>文件名匹配字符(可以包含*和?)</param>
  public void Put(string strFolder,string strFileNameMask)
  {
   string[] strFiles = Directory.GetFiles(strFolder,strFileNameMask);
   foreach(string strFile in strFiles)
   {
    //strFile是完整的文件名(包含路径)
    Put(strFile);
   }
  }
   

  /// <summary>
  /// 上传一个文件
  /// </summary>
  /// <param>本地文件名</param>
  public void Put(string strFileName)
  {
   if(!bConnected)
   {
    Connect();
   }
   Socket socketData = CreateDataSocket();
   SendCommand("STOR "+Path.GetFileName(strFileName));
   if( !(iReplyCode == 125 || iReplyCode == 150) )
   {
    throw new IOException(strReply.Substring(4));
   }
   FileStream input = new
   FileStream(strFileName,FileMode.Open);
   int iBytes = 0;
   while ((iBytes = input.Read(buffer,0,buffer.Length)) > 0)
   {
    socketData.Send(buffer, iBytes, 0);
   }
   input.Close();
   if (socketData.Connected)
   {
    socketData.Close();
   }
   if(!(iReplyCode == 226 || iReplyCode == 250))
   {
    ReadReply();
    if(!(iReplyCode == 226 || iReplyCode == 250))
    {
     throw new IOException(strReply.Substring(4));
    }
   }
  }
   
  #endregion

  #region 目录操作
  /// <summary>
  /// 创建目录
  /// </summary>
  /// <param>目录名</param>
  public void MkDir(string strDirName)
  {
   if(!bConnected)
   {
    Connect();
   }
   SendCommand("MKD "+strDirName);
   if(iReplyCode != 257)
   {
    throw new IOException(strReply.Substring(4));
   }
  }
   
 
  /// <summary>
  /// 删除目录
  /// </summary>
  /// <param>目录名</param>
  public void RmDir(string strDirName)
  {
   if(!bConnected)
   {
    Connect();
   }
   SendCommand("RMD "+strDirName);
   if(iReplyCode != 250)
   {
    throw new IOException(strReply.Substring(4));
   }
  }
   
 
  /// <summary>
  /// 改变目录
  /// </summary>
  /// <param>新的工作目录名</param>
  public void ChDir(string strDirName)
  {
   if(strDirName.Equals(".") || strDirName.Equals(""))
   {
    return;
   }
   if(!bConnected)
   {
    Connect();
   }
   SendCommand("CWD "+strDirName);
   if(iReplyCode != 250)
   {
    throw new IOException(strReply.Substring(4));
   }
   this.strRemotePath = strDirName;
  }
   
  #endregion

  #region 内部变量
  /// <summary>
  /// 服务器返回的应答信息(包含应答码)
  /// </summary>
  private string strMsg;
  /// <summary>
  /// 服务器返回的应答信息(包含应答码)
  /// </summary>
  private string strReply;
  /// <summary>
  /// 服务器返回的应答码
  /// </summary>
  private int iReplyCode;
  /// <summary>
  /// 进行控制连接的socket
  /// </summary>
  private Socket socketControl;
  /// <summary>
  /// 传输模式
  /// </summary>
  private TransferType trType;
  /// <summary>
  /// 接收和发送数据的缓冲区
  /// </summary>
  private static int BLOCK_SIZE = 512;
  Byte[] buffer = new Byte[BLOCK_SIZE];
  /// <summary>
  /// 编码方式
  /// </summary>
  Encoding ASCII = Encoding.ASCII;
  #endregion

  #region 内部函数
  /// <summary>
  /// 将一行应答字符串记录在strReply和strMsg
  /// 应答码记录在iReplyCode
  /// </summary>
  private void ReadReply()
  {
   strMsg = "";
   strReply = ReadLine();
   iReplyCode = Int32.Parse(strReply.Substring(0,3));
  }

  /// <summary>
  /// 建立进行数据连接的socket
  /// </summary>
  /// <returns>数据连接socket</returns>
  private Socket CreateDataSocket()
  {
   SendCommand("PASV");
   if(iReplyCode != 227)
   {
    throw new IOException(strReply.Substring(4));
   }
   int index1 = strReply.IndexOf('(');
   int index2 = strReply.IndexOf(')');
   string ipData =
    strReply.Substring(index1+1,index2-index1-1);
   int[] parts = new int[6];
   int len = ipData.Length;
   int partCount = 0;
   string buf="";
   for (int i = 0; i < len && partCount <= 6; i++)
   {
    char ch = Char.Parse(ipData.Substring(i,1));
    if (Char.IsDigit(ch))
     buf+=ch;
    else if (ch != ',')
    {
     throw new IOException("Malformed PASV strReply: " +
      strReply);
    }
    if (ch == ',' || i+1 == len)
    {
     try
     {
      parts[partCount++] = Int32.Parse(buf);
      buf="";
     }
     catch (Exception)
     {
      throw new IOException("Malformed PASV strReply: " +
       strReply);
     }
    }
   }
   string ipAddress = parts[0] + "."+ parts[1]+ "." +
    parts[2] + "." + parts[3];
   int port = (parts[4] << 8) + parts[5];
   Socket s = new
    Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
   IPEndPoint ep = new
    IPEndPoint(IPAddress.Parse(ipAddress), port);
   try
   {
    s.Connect(ep);
   }
   catch(Exception)
   {
    throw new IOException("Can't connect to remote server");
   }
   return s;
  }

  /// <summary>
  /// 关闭socket连接(用于登录以前)
  /// </summary>
  private void CloseSocketConnect()
  {
   if(socketControl!=null)
   {
    socketControl.Close();
    socketControl = null;
   }
   bConnected = false;
  }
 
  /// <summary>
  /// 读取Socket返回的所有字符串
  /// </summary>
  /// <returns>包含应答码的字符串行</returns>
  private string ReadLine()
  {
   while(true)
   {
    int iBytes = socketControl.Receive(buffer, buffer.Length, 0);
    strMsg += ASCII.GetString(buffer, 0, iBytes);
    if(iBytes < buffer.Length)
    {
     break;
    }
   }
   char[] seperator = {'\n'};
   string[] mess = strMsg.Split(seperator);
   if(strMsg.Length > 2)
   {
    strMsg = mess[mess.Length-2];
    //seperator[0]是10,换行符是由13和0组成的,分隔后10后面虽没有字符串,
    //但也会分配为空字符串给后面(也是最后一个)字符串数组,
    //所以最后一个mess是没用的空字符串
    //但为什么不直接取mess[0],因为只有最后一行字符串应答码与信息之间有空格
   }
   else
   {
    strMsg = mess[0];
   }
   if(!strMsg.Substring(3,1).Equals(" "))//返回字符串正确的是以应答码(如220开头,后面接一空格,再接问候字符串)
   {
    return ReadLine();
   }
   return strMsg;
  }

  /// <summary>
  /// 发送命令并获取应答码和最后一行应答字符串
  /// </summary>
  /// <param>命令</param>
  private void SendCommand(String strCommand)
  {
   Byte[] cmdBytes =
   Encoding.ASCII.GetBytes((strCommand+"\r\n").ToCharArray());
   socketControl.Send(cmdBytes, cmdBytes.Length, 0);
   ReadReply();
  }

  #endregion
 }
}