电子邮件系统 4----JavaMail SMTP服务器发送邮件程序示例 .

/**
 * JavaMail SMTP服务器发送邮件程序示例
 * 扮演SMTP服务器角色与邮件客户端软件最大的区别就是：
 * SMTP服务器需要解析不同接收人邮件地址主机名对应的SMTP服务器主机名
 * ，同时不需要验证
 * 注意：由于条件的限制，此程序是运行不成功的，原因见下面的注释说明
 */
 package com.labci.javamail.test;
 import java.util.Date;
 import java.util.Properties;
 import javax.mail.Message.RecipientType;
 import javax.mail.Message;
 import javax.mail.MessagingException;
 import javax.mail.Session;
 import javax.mail.Transport;
 import javax.mail.internet.AddressException;
 import javax.mail.internet.InternetAddress;
 import javax.mail.internet.MimeMessage;
 import javax.naming.NamingException;
 import javax.naming.directory.Attributes;
 import javax.naming.directory.DirContext;
 import javax.naming.directory.InitialDirContext;
 /**
 * @author Bill Tu
 * @since May 27, 2011(12:21:41 PM)
 *
 */
 public class SMTPSenderTest {
      public static String  getSMTPHost(String domain,String dnsServer) throws NamingException{
           DirContext ctx=new InitialDirContext();
           Attributes mxAttrs=null;
           if(null != dnsServer){
               mxAttrs=ctx.getAttributes("dns://"+dnsServer+"/"+domain,new String[]{"MX"});
           }else{
               mxAttrs=ctx.getAttributes("dns:/"+domain,new String[]{"MX"});
          }

           String mx=(String) mxAttrs.get("MX").get();
           String smtpServerName=mx.substring(mx.indexOf(" ")+1);
           return smtpServerName;
     }

      private static Message getMessage(Session session) throws AddressException, MessagingException{
           String from="[email protected]";
           String subject="hello";
           String content="this is content";

           MimeMessage msg=new MimeMessage(session);
           msg.setFrom(new InternetAddress(from));
          msg.setSubject(subject);
          msg.setText(content);
           msg.setSentDate(new Date());

           return msg;

     }

      private static Session getSession(){
           Properties props=new Properties();
           //设置ehlo命令中的主机名,若检测到主机名与其IP地址一致，则认为这时的发送方是SMTP服务器，就不需要验证;否则就是邮件客户端软件，则需要验证。
           props.put("mail.smtp.localhost", "mail.digu.com");
           props.put("mail.smtp.auth", "false");
           props.put("mail.smtp.port", "25");
          Session session=Session.getDefaultInstance(props);
           session.setDebug(true);
           return session;
     }

      @SuppressWarnings("static-access")
      private static void sendEmail(Message message,Session session,String to)
        throws AddressException, MessagingException, NamingException{
          message.setRecipients(RecipientType.TO, InternetAddress.parse(to));
          message.saveChanges();

           Transport transport=session.getTransport("smtp");

           String domain=to.substring(to.indexOf("@")+1);
           String host=getSMTPHost(domain,null);

           transport.connect(host, null, null);
          transport.send(message, message.getRecipients(Message.RecipientType.TO));

          transport.close();
     }

      public static void main(String []args)
       throws AddressException, MessagingException, NamingException{
           String []to=new String[]{"[email protected]","[email protected]"};
          Session session=getSession();
          Message msg=getMessage(session);
           for(String email:to){
              sendEmail(msg,session,email);
          }
     }
}