基本原理就是先建立Socket连接，然后发请求命令和取回应答码。编码方式采用Encoding ASCII = Encoding.Default;来支持中文文件名。
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.IO;
namespace Kostech.Net
{
/// <summary>
/// FTP 的摘要说明。
/// </summary>
public class FTP
{
private string strRemoteHost;
private int strRemotePort;
private string strRemotePath;
private string strRemoteUser;
private string strRemotePass;
private Boolean bConnected;
#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>
/// 传输模式:二进制类型、ASCII类型
/// </summary>
public enum TransferType
{
/// <summary>
/// Binary
/// </summary>
Binary,
/// <summary>
/// ASCII
/// </summary>
ASCII
};
/// <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.Default;
#endregion
#region 内部函数
#region 构造函数
/// <summary>
/// 缺省构造函数
/// </summary>
public FTP()
{
strRemoteHost = "";
strRemotePath = "";
strRemoteUser = "";
strRemotePass = "";
strRemotePort = 21;
bConnected = false;
}
/// <summary>
/// 构造函数
/// </summary>
/// <param name="remoteHost"></param>
/// <param name="remotePath"></param>
/// <param name="remoteUser"></param>
/// <param name="remotePass"></param>
/// <param name="remotePort"></param>
public FTP( 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>
public string RemoteHost
{
get
{
return strRemoteHost;
}
set
{
strRemoteHost = value;
}
}
/// <summary>
/// FTP服务器端口
/// </summary>
public int RemotePort
{
get
{
return strRemotePort;
}
set
{
strRemotePort = value;
}
}
/// <summary>
/// 当前服务器目录
/// </summary>
public string RemotePath
{
get
{
return strRemotePath;
}
set
{
strRemotePath = value;
}
}
/// <summary>
/// 登录用户账号
/// </summary>
public string RemoteUser
{
set
{
strRemoteUser = value;
}
}
/// <summary>
/// 用户登录密码
/// </summary>
public string RemotePass
{
set
{
strRemotePass = value;
}
}
/// <summary>
/// 是否登录
/// </summary>
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>
/// 设置传输模式
/// </summary>
/// <param name="ttType">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 name="strMask">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 name="strFileName">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 name="strFileName">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 name="strOldFileName">旧文件名</param>
/// <param name="strNewFileName">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 name="strFileNameMask">文件名的匹配字符串</param>
/// <param name="strFolder">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 name="strRemoteFileName">要下载的文件名</param>
/// <param name="strFolder">本地目录(不得以/结束)</param>
/// <param name="strLocalFileName">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 name="strFolder">本地目录(不得以/结束)</param>
/// <param name="strFileNameMask">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 name="strFileName">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 name="strDirName">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 name="strDirName">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 name="strDirName">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
/// <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 name="strCommand">命令</param>
private void SendCommand(string strCommand)
{
Byte[] cmdBytes = ASCII.GetBytes((strCommand + "/r/n").ToCharArray());
socketControl.Send(cmdBytes, cmdBytes.Length, 0);
ReadReply();
}
#endregion
}
}
很多人都找我要调用的方法，其实有了类库就很简单了，我大概写一下吧
FTP myftp = new FTP([ftp主机], [主机目录], [ftp用户名], [ftp用户密码], [ftp端口]);
myftp.Put( [本地文件全路径]); // 上传到服务器中
myftp.Get([ftp文件名称（可以是通配符表示）], [本地存放路径]); //下载到本地
其它方法的使用可以参考我代码中的注释
