JavaMail SMTP服务器发送邮件程序示例 java通过dns服务器解析ip地址

/**
 * 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
 */

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="iwtxokhtd@163.com";
		  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[]{"277515444@qq.com","277515445@qq.com"};
		  Session session=getSession();
		  Message msg=getMessage(session);
		  for(String email:to){
			  sendEmail(msg,session,email);
		  }
	 }
}