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);
}
}
}