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="[e-mail]";
          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[]{"[e-mail]","[e-mail]"};
          Session session=getSession();
          Message msg=getMessage(session);
          for(String email:to){
              sendEmail(msg,session,email);
          }
     }
}