c# 实现pop3收邮件

using System.Net.Sockets;
using System.Collections;
using System.IO;
using System.Net;
using System;
using System.Web.Mail;

public class POP3
{
   string POPServer;
   string user;
   string pwd;
   NetworkStream ns;
   StreamReader sr;
   static int count;
   //调用Srfile类，写入文件内容和文件名,文件格式：.txt 读邮件信息
   // Srfile Filesr = new Srfile();

   //对邮件标题 base64 解码
   /// <summary>
   /// base64 解码
   /// </summary>
   /// <param name="code"></param>
   /// <returns></returns>
   private string DecodeBase64(string code) //string code_type,
   {
    string decode = "";
    string st = code+"000";//
    string   strcode = st.Substring(0,(st.Length/4)*4);
    byte[] bytes = Convert.FromBase64String(strcode);
    try
    {
     decode = System.Text.Encoding.GetEncoding("GB2312").GetString(bytes);
    }
    catch
    {
     decode = code;
    }
    return decode;
   }

   //对邮件标题解码 quoted-printable
   /// <summary>
   /// quoted-printable 解码
   /// </summary>
   /// <param name="code"></param>
   /// <returns></returns>
   private string DecodeQ(string code)
   {
       
    string[] textArray1 = code.Split(new char[] { '=' });
    byte[] buf = new byte[textArray1.Length];
    try
    {
  
     for (int i =0;i<textArray1.Length;i++)
     {
      if (textArray1[i].Trim()!=string.Empty)
      {
   
       byte[] buftest = new byte[2];
            
       buf[i] = (byte) int.Parse(textArray1[i].Substring(0,2),System.Globalization.NumberStyles.HexNumber);

      }
     }
    }
    catch
    {
     return null;
    }
    return System.Text.Encoding.Default.GetString(buf);
   }

   public POP3(){}

   #region
   /// <summary>
   /// 接收邮件服务器相关信息
   /// </summary>
   /// <param name="server">参数 pop邮件服务器地址 </param>
   /// <param name="user">参数 登录到pop邮件服务器的用户名 </param>
   /// <param name="pwd">参数 登录到pop邮件服务器的密码</param>
   /// <returns>无返回</returns>
   public POP3(string server, string _user, string _pwd)
   {
    POPServer = server;
    user = _user;
    pwd = _pwd;
   }
   #endregion
   //登陆服务器
   private void Connect()
   {
    TcpClient sender = new TcpClient(POPServer,110);
    Byte[] outbytes;
    string input;
    string readuser = string.Empty;
    string readpwd = string.Empty;
    try
    {
     ns = sender.GetStream();
     sr = new StreamReader(ns);
     sr.ReadLine();
     //检查密码
     input = "user " + user + "rn";
     outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
     ns.Write(outbytes,0,outbytes.Length) ;

     readuser = sr.ReadLine();
     input = "pass " + pwd + "rn";
     outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
     ns.Write(outbytes,0,outbytes.Length) ;
     readpwd = sr.ReadLine();
     //Console.WriteLine(sr.ReadLine() );
    
    }
    catch
    {
     System.Windows.Forms.MessageBox.Show("用户名或密码错误");
    }
   }
   //为了读到数据流中的正确信息，重新建的一个方法（只是在读邮件详细信息是用到《即GetNewMessages（）方法中用到，这样就可以正常显示邮件正文的中英文》）
   private void Connecttest(TcpClient tcpc)
   {
    Byte[] outbytes;
    string input;
    string readuser = string.Empty;
    string readpwd = string.Empty;
    try
    {
     ns = tcpc.GetStream();
     sr = new StreamReader(ns);

     sr.ReadLine();
     //Console.WriteLine(sr.ReadLine() );

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

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

    }
    catch
    {
     System.Windows.Forms.MessageBox.Show("用户名或密码错误");
    }
   }
   //断开与服务器的连接
   private void Disconnect()
   {
    //"quit" 即表示断开连接
    string input = "quit" + "rn";
    Byte[] outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length);
    //关闭数据流
    ns.Close();
   }
   //获得新邮件数目
   # region
   /// <summary>
   /// 获取邮件数目
   /// </summary>
   /// <returns>返回 int 邮件数目</returns>
   public int GetNumberOfNewMessages()
   {
    Byte[] outbytes;
    string input;

    int countmail;

    try
    {
     Connect();
     //"stat"向邮件服务器 表示要取邮件数目
     input = "stat" + "rn";
     //将string input转化为7位的字符，以便可以在网络上传输
     outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
     ns.Write(outbytes,0,outbytes.Length);
     string thisResponse = sr.ReadLine();
     if (thisResponse.Substring(0,4) == "-ERR")
     {
      return -1;
     }
     string[] tmpArray;
     //将从服务器取到的数据以“”分成字符数组
     tmpArray=thisResponse.Split(' ');
     //断开与服务器的连接
     Disconnect();
     //取到的表示邮件数目
     countmail = Convert.ToInt32(tmpArray[1]);
     count = countmail;
     return countmail;

    }
    catch
    {
     System.Windows.Forms.MessageBox.Show("Could not connect to mail server");
     return -1;//表示读邮件时 出错，将接收邮件的线程 阻塞5分钟
    }
   }
   # endregion
   
   //获取邮件
   # region
   /// <summary>
   /// 获取所有新邮件
   /// </summary>
   /// <returns> 返回 ArrayList</returns>

   public ArrayList GetNewMessages( )   //public ArrayList GetNewMessages(string subj)
   {

    bool blag = false;
    int newcount = GetNumberOfNewMessages();
    ArrayList newmsgs = new ArrayList();

    try
    {
     TcpClient tcpc = new TcpClient(POPServer,110);
     Connecttest(tcpc);
     //    newcount = GetNumberOfNewMessages();

     for(int n =1; n<newcount+1; n++)
     {
      ArrayList msglines = GetRawMessage(tcpc,n);
      string msgsubj = GetMessageSubject(msglines).Trim();

      System.Web.Mail.MailMessage msg = new MailMessage();

      //首先判断Substring是什么编码（"=?gb2312?B?"或者"=?gb2312?Q?"），然后转到相应的解码方法，实现解码
      //如果是"=?gb2312?B?"，转到DecodeBase64（）进行解码
      if (msgsubj.Length>11)
      {
       //base64编码
       if (msgsubj.Substring(0,11)=="=?gb2312?B?")
       {
        blag = true;

        msgsubj = msgsubj.Substring(11,msgsubj.Length-13);
        msg.Subject = DecodeBase64(msgsubj);
       }
       //如果是"=?gb2312?Q?"编码，先得取到被编码的部分，字符如果没编码就不转到解码方法
       if(msgsubj.Length>11)
       {

     
        if (msgsubj.Substring(0,11)=="=?gb2312?Q?")
        {
         blag = true;
         msgsubj = msgsubj.Substring(11,msgsubj.Length-13);
         string text = msgsubj;
         string str = string.Empty;
         string decodeq = string.Empty;
         while(text.Length>0)
         {
          //判断编码部分是否开始
          if (text.Substring(0,1)=="=")
          {
           decodeq = text.Substring(0,3);
           text = text.Substring(3,text.Length-3);
           //当出现编码部分时，则取出连续的编码部分
           while (text.Length>0)
           {
            if(text.Substring(0,1) == "=")
            {
             decodeq +=text.Substring(0,3);
             text = text.Substring(3,text.Length-3);

            }
            else
            {
             break;
            }
           }
           //将连续的编码进行解码
           str += DecodeQ(decodeq);

          }
           //如果该字节没编码，则不用处理
          else
          {
           str += text.Substring(0,1);
           text = text.Substring(1,text.Length-1);
          }
      
         }
         //用空格代替subject中的“0”,以便能取道全部的内容
         msg.Subject = str.Replace("0"," ");
        }
       }
       if (blag == false)
       {
        msg.Subject = msgsubj.Replace("0"," ");
       }
     
   
      }
      else
      {
       msg.Subject = msgsubj.Replace("0"," ");
      }

      blag = false;

      //取发邮件者的邮件地址
      msg.From = GetMessageFrom(msglines);
      //取邮件正文
      string msgbody = GetMessageBody(msglines);
      msg.Body = msgbody;
      newmsgs.Add(msg);
    
      //将收到的邮件保存到本地，调用另一个类的保存邮件方法，不使用此功能
      //     Filesr.Savefile("subject:"+msg.Subject+"rn"+"sender:"+msg.From+"rn"+"context:"+msg.Body,"mail"+n+".txt");
      //删除邮件，不使用
      //      DeleteMessage(n);
     }
     //断开与服务器的连接
     Disconnect();
     return newmsgs;
    }
    catch
    {
//     System.Windows.Forms.MessageBox.Show("读取邮件出错，请重试");
     return newmsgs;
    }
   }
   #endregion
   //从服务器读邮件信息
   private ArrayList GetRawMessage (TcpClient tcpc,int messagenumber)
   {
    Byte[] outbytes;
    string input;
    string line = "";
    input = "retr " + messagenumber.ToString() + "rn";
    outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length);

    ArrayList msglines = new ArrayList();
    StreamReader srtext;
    srtext = new StreamReader(tcpc.GetStream(),System.Text.Encoding.Default);
    //每份邮件以英文“.”结束
    do
    {
     line = srtext.ReadLine();
     msglines.Add(line);
    } while (line != ".");
    msglines.RemoveAt(msglines.Count-1);

    return msglines;
   }
   //获取邮件标题
   private string GetMessageSubject(ArrayList msglines)
   {
    IEnumerator msgenum = msglines.GetEnumerator();
    while (msgenum.MoveNext() )
    {
     string line = (string)msgenum.Current;
     if(line.StartsWith("Subject:") )
     {
      return line.Substring(8,line.Length-8);
     }
    }
    return "None";
   }
   //获取邮件的发送人地址
   private string GetMessageFrom (ArrayList msglines)
   {
    string[] tokens;
    IEnumerator msgenum = msglines.GetEnumerator();
    while (msgenum.MoveNext() )
    {
     string line = (string)msgenum.Current;
     if(line.StartsWith("From") )
     {
      tokens = line.Split(new Char[] {':'});
      return tokens[1].Trim(new Char[] {'<','>',' '});
     }
    }
    return "None";
   }

   //邮件正文
   private string GetMessageBody(ArrayList msglines)
   {
    string body = "";
    string line = " ";
    IEnumerator msgenum = msglines.GetEnumerator();

    while(line.CompareTo("") != 0)
    {
     msgenum.MoveNext();
     line = (string)msgenum.Current;
    }

    while (msgenum.MoveNext() )
    {
     body = body + (string)msgenum.Current + "rn";
    }
    return body;
   }
   //删除第几封邮件
   #region
   /// <summary>
   ///根据输入的数字，删除相应编号的邮件
   /// </summary>
   /// <param name="messagenumber">参数 删除第几封邮件 </param>
   /// <returns>返回 bool true成功；false 失败</returns>
   public bool DeleteMessage(int messagenumber)
   {
    Connect();
    Byte[] outbytes;
    string input ;
    byte[] backmsg = new byte[25];
    string msg = string.Empty;
  
    try
    {
     input = "dele " + messagenumber.ToString() + "rn";
     outbytes = System.Text.Encoding.ASCII.GetBytes(input.ToCharArray());
     ns.Write(outbytes,0,outbytes.Length);
     ns.Read(backmsg,0,25);
     msg = System.Text.Encoding.Default.GetString(backmsg,0,backmsg.Length);
     Disconnect();
     if (msg.Substring(0,3)=="+OK")
     {
      return true;
     }
     return false;
    }
    catch(Exception e)
    {
     return false;
    }

   }
   #endregion

}