电子邮件那点事儿

电子邮件那点事儿

package  org.hvp.test;

import  java.util.Hashtable;

import  javax.naming.NamingException;
import  javax.naming.directory.Attributes;
import  javax.naming.directory.DirContext;
import  javax.naming.directory.InitialDirContext;

/**
 *  @author  "惠万鹏"
 *
  */
public   class  Smtp
{
     public   static  String getSmtpServer(String dns, String domain)
             throws  NamingException
    {
         /**  如果domain传入的是一个email  */
         if  (domain.indexOf( " @ " )  >   0 )
        {
            domain  =  domain.substring(domain.indexOf( " @ " )  +   1 );
        }
        Hashtable < String, String >  properties  =   new  Hashtable < String, String > ();
        properties.put( " java.naming.factory.initial " , " com.sun.jndi.dns.DnsContextFactory " );
        properties.put( " java.naming.provider.url " ,  " dns:// "   +  dns);
        DirContext ctx  =   new  InitialDirContext(properties);
        Attributes attributes  =  ctx.getAttributes(domain,  new  String[] {  " MX "  });
        String recordMx  =  (String) attributes.get( " MX " ).get();
         if  (recordMx  !=   null )
        {
            recordMx  =  recordMx.substring(recordMx.indexOf( "   " )  +   1 );
        }
        System.out.println( " --------> "   +  recordMx  +   " <------- " );
         return  recordMx;
    }
    
    
    
     public   static   void  main(String[] args)  throws  NamingException
    {
        Smtp.getSmtpServer( " 10.1.3.210 " ,  " [email protected] " ); 
    }
}

package  org.hvp.test;

import  java.net. * ;
import  java.io. * ;

public   class  Test {

     private   static  String END_FLAG  =   " \r\n " ;

     public   static   void  main(String[] args)  throws  Exception {
        String mx  =   " 163mx00.mxmail.netease.com " ;
        InetAddress addr  =  InetAddress.getByName(mx);
        Socket socket  =   new  Socket(addr,  25 );

        InputStream in  =  socket.getInputStream();
        OutputStream out  =  socket.getOutputStream();

         //  连接成功后服务器会响应：
        response(in);

         //  首先发送HELO命令：
        send( " HELO www.javasprite.com "   +  END_FLAG, out);
        response(in);

         //  然后发送发件人地址：
        send( " MAIL FROM: [email protected] "   +  END_FLAG, out);
        response(in);

         //  设置收件人地址：
        send( " RCPT TO: [email protected] "   +  END_FLAG, out);
        response(in);

         //  开始发送邮件正文：
        send( " DATA "   +  END_FLAG, out);
        response(in);

        send( " From: [email protected] "   +  END_FLAG, out);
        send( " To: [email protected] "   +  END_FLAG, out);
        send( " Subject: Test without smtp server "   +  END_FLAG, out);
        send( " Content-Type: text/plain; "   +  END_FLAG, out);
        send(END_FLAG  +  END_FLAG, out);

         //  发送邮件正文，如果用中文，需要BASE64编码：
        send( " text message body! "   +  END_FLAG, out);
         //  每行以\r\n结束，不可过长，可拆成多行。

         //  以"\r\n.\r\n"作为结束标志：
        send(END_FLAG  +   " . "   +  END_FLAG, out);
        response(in);

         //  结束并确认发送：
        send( " QUIT "   +  END_FLAG, out);
        response(in);
        in.close();
        out.close();
        socket.close();
    }

     public   static   void  response(InputStream in)  throws  Exception {
         byte [] buffer  =   new   byte [ 102400 ];
         int  n  =  in.read(buffer);
         if (n > 0 ){
            String s  =   new  String(buffer,  0 , n);
            System.out.println(s);
        }
    }

     public   static   void  send(String s, OutputStream out)  throws  Exception {
         byte [] buffer  =  s.getBytes();
         if (buffer  !=   null   &&  buffer.length > 0 )
        {
            out.write(buffer);
            out.flush();
        }
    }
}