如何使用C#访问POP3服务器

Requirement:

Requires .NET SDK

How To Compile?

csc /r:System.Net.dll /r:System.IO.dll pop.cs 

Source Code

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

class POP
{
string POPServer;
string user;
string pwd;
public POP(){}
public POP(string server, string _user, string _pwd)
{
POPServer = server;
user = _user;
pwd = _pwd;
}
private NetworkStream Connect()
{
TCPClient sender = new TCPClient(POPServer,110);
Byte[] outbytes;
string input;
NetworkStream ns = null;
try{
ns = sender.GetStream();
StreamReader sr = new StreamReader(ns);
Console.WriteLine(sr.ReadLine() );

input = "user " + user + "rn";
outbytes = System.Text.Encoding.ASCII.GetBytes
(input.ToCharArray());
ns.Write(outbytes,0,outbytes.Length) ;
Console.WriteLine(sr.ReadLine() );

input = "pass " + pwd + "rn";
outbytes = System.Text.Encoding.ASCII.GetBytes
(input.ToCharArray());
ns.Write(outbytes,0,outbytes.Length) ;
Console.WriteLine(sr.ReadLine() );

return ns;
}
catch(InvalidOperationException ioe){
Console.WriteLine("Could not connect to mail server");
return ns;
}
}
public int GetNumberOfNewMessages()
{
Byte[] outbytes;
string input;
try{
NetworkStream ns = Connect();
StreamReader sr = new StreamReader(ns);

input = "stat" + "rn";
outbytes = System.Text.Encoding.ASCII.GetBytes
(input.ToCharArray());
ns.Write(outbytes,0,outbytes.Length);
string resp = sr.ReadLine();
Console.WriteLine(resp);
string[] tokens = resp.Split(new Char[] {' '});

input = "quit" + "rn";
outbytes = System.Text.Encoding.ASCII.GetBytes
(input.ToCharArray());
ns.Write(outbytes,0,outbytes.Length);
Console.WriteLine(sr.ReadLine());

sr.Close();
ns.Close();
return tokens[1].ToInt32();
}
catch(InvalidOperationException ioe){
Console.WriteLine("Could not connect to mail server");
return 0;
}
}
public static void Main()
{
POP pop = new POP("pop-server", "loginname", "password");
Console.WriteLine("New Messages = {0}",
pop.GetNumberOfNewMessages() );
Console.ReadLine();
}
}  

======================
命令解析部分

private bool SwitchCommand(string POP3_commandTxt)
  {
   try
   {
    //---- Parse command --------------------------------------------------//
    string[] cmdParts = POP3_commandTxt.TrimStart().Split(new char[]{' '});
    string POP3_command = cmdParts[0];
        POP3_command = POP3_command.ToUpper();
    //---------------------------------------------------------------------//

    //----- loging stuff --------------------------------------------------------------------------//
    if(m_pPOP3_Server.LogCommands){
     string lCmdTxt = POP3_commandTxt.Replace("rn","");
     m_pLogWriter.AddEntry(lCmdTxt,this.SessionID,m_ConnectedIp,"C");
    }
    //---- End of loging ---------------------------------------------------------------------------//

    switch(POP3_command)
    {
     case "USER":
      USER(Core.GetArgsText(POP3_commandTxt,"USER"));
      break;

     case "PASS":
      PASS(Core.GetArgsText(POP3_commandTxt,"PASS"));
      break;
     
     case "STAT":
      STAT();
      break;

     case "LIST":
      LIST(Core.GetArgsText(POP3_commandTxt,"LIST"));
      break;

     case "RETR":     
      RETR(Core.GetArgsText(POP3_commandTxt,"RETR"));
      break;

     case "DELE":
      DELE(Core.GetArgsText(POP3_commandTxt,"DELE"));
      break;

     case "NOOP":
      NOOP();
      break;

     case "RSET":
      RSET();
      break;

     case "QUIT":
      QUIT();
      return true;

     //----- Optional commands ----- //
     case "UIDL":
      UIDL(Core.GetArgsText(POP3_commandTxt,"UIDL"));
      break;

     case "APOP":
      APOP(Core.GetArgsText(POP3_commandTxt,"APOP"));
      break;

     case "TOP":
      TOP(Core.GetArgsText(POP3_commandTxt,"TOP"));
      break;
          
     default:     
      SendData("-ERR Invalid commandrn");

      //---- Check that maximum bad commands count isn't exceeded ---------------//
      if(m_BadCmdCount > m_pPOP3_Server.MaxBadCommands-1){
       SendData("421 Too many bad commands, closing transmission channelrn");
       return true;
      }
      m_BadCmdCount++;
      //-------------------------------------------------------------------------//

      break;
    
    }
   }
   catch(Exception x)
   {
    // Connection lost
    if(!m_pClientSocket.Connected){
     return true;
    }
    
    SendData("-ERR Unkown temp errorrn");
    m_pPOP3_Server.OnSysError(x,new System.Diagnostics.StackTrace());
   }
   
   return false;
  }

===========================
我做了一个pop3接收客户端，在收取邮件时，服务器返回得内容如下：

+OK Return-Path: Delivered-To: yysscheng@sina.comReceived: (qmail 32409 invoked from network); 28 Nov 2002 01:31:31 -0000Received: from unknown (HELO 21cn.com) (61.140.60.248)  by 202.106.187.186 with SMTP; 28 Nov 2002 01:31:31 -0000Received: from 21cn.com([127.0.0.1]) by 21cn.com(AIMC 2.9.5.6) with SMTP id jm93de57653; Thr, 28 Nov 2002 09:48:55 +0800Received: from 21cn.com([10.2.2.1]) by 21cn.com(AIMC 2.9.5.1) with SMTP id jm73de5e038; Thr, 28 Nov 2002 09:48:55 +0800Content-Type: text/plainContent-Transfer-Encoding: 8bitMIME-Version: 1.0Message-ID: X-AIMailer: AIMC 2.9.5.6 2002.10.10X-AIMime: MIME/SMIME Lib 2.9 2.9 2002.10.10Date: Thu, 28 Nov 2002 09:34:33 +0800 (CST)From: "??????"To: yysscheng Cc: Subject: =?gb2312?b?sOy5q9fUtq+7rw==?=X-Priority: 3X-Originating-IP: 61.163.14.2X-AIMC-AUTH: (null)X-AIMC-MAILFROM: com_com@21cn.com??????    ??????????????????????????    ??????????                          ??????             11.28----------------------------------------------?????????????????????????????????? http://y.21cn.com ????A??210099???????????????????? http://sms.21cn.com/baobei/sjsy.html 21CN??????3??????12??10?????????? http://mail.21cn.com/huodong/9yue/ 21CN????????????????????????U?? http://mail.21cn.com/huodong/11yue/business/

其中的汉字如何解析出来？
（注：我得连接类如下：
public class Pop3Connection
 {
  private TcpClient socket;
  private StreamReader reader;
  private StreamWriter writer;
  private bool connected;
  public bool Connected
  {
   get{return connected;}
  }
  public Pop3Connection()
  {
   // TODO: 在此处添加构造函数逻辑
   connected=false;
   socket=new TcpClient();
  }
  ~Pop3Connection()
  {
   socket=null;
  }
  internal void Open(string host,int port)
  {
   if(host==null || host.Trim()=="")
   {
    throw new ArgumentException("Host is null!");
   }
   if(port<0)
   {
    throw new ArgumentException("Port is invalid!");
   }
   try
   {

    socket.Connect(host,port);
    reader=new StreamReader(socket.GetStream(),System.Text.Encoding.ASCII );
    writer=new StreamWriter(socket.GetStream(),System.Text.Encoding.ASCII);
    connected=true;
   }
   catch(Exception e)
   {
    connected=false;
   }
  }
  internal void SendCommand(string cmd)
  {
   writer.WriteLine(cmd);
   writer.Flush();
  }
  internal void GetReply(out string reply )
  {
   if(Connected)
   {reply=reader.ReadLine();}
   else
   {reply="";}
  }
  internal void Close()
  {
   reader.Close();
   writer.Flush();
   writer.Close();
   reader=null;
   writer=null;
   socket.Close();
   connected=false;
  }
 }
）