怎样用javamail实现smtp服务器的发送认证。

                       谢谢！

props.put("mail.smtp.auth", "true");
props.put("mail.smtp.user", userId);
props.put("mail.smtp.password",password);
session = javax.mail.Session.getInstance(props,new MyAuthenticator(userId, password));

其中的MyAuthenticator

import javax.mail.*;

public  class MyAuthenticator extends Authenticator{
  String userId;
  String password;
  public MyAuthenticator(String userId, String password){
    this.userId = userId;
    this.password = password;
  }
  public PasswordAuthentication getPasswordAuthentication(){
    return new PasswordAuthentication(userId, password);
  }
}

import javax.mail.*;
import javax.mail.internet.*;
import java.util.*;


public class sendMail
{
      public static void main(String args[]) throws Exception
      {

            String host = "smtp.sina.com.cn";
            String from =   "javamail@sina.com";
            String to = "javamail@china.com";
            String username = "javamail";
            String password = "password";

            // Get system properties
            // Properties props = System.getProperties(); 很多例子中是这样的，其实下面这句更好，可以用在applet中
            Properties props = new Properties();

            // Setup mail server
            props.put("mail.smtp.host", host);
            props.put("mail.smtp.auth", "true"); //这样才能通过验证

            // Get session
            Session session = Session.getDefaultInstance(props);

            // watch the mail commands go by to the mail server
            session.setDebug(true);

            // Define message
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(from));
            message.addRecipient(Message.RecipientType.TO,
               new InternetAddress(to));
            message.setSubject("Hello JavaMail");
            message.setText("Welcome to JavaMail");

            // Send message
            message.saveChanges();
            Transport transport = session.getTransport("smtp");
            transport.connect(host, username, password);
            transport.sendMessage(message, message.getAllRecipients());
            transport.close();
      }
}