有没有一种方法可以从javax.mail.Authenticator获取用户名和密码?它是如何工作的？

import javax.mail.Authenticator;
import javax.mail.PasswordAuthentication;

public class MyAuthenticator extends Authenticator {
    private String username;
    private String password;

    public MyAuthenticator(String username, String password) {
        this.username = username;
        this.password = password;
    }

    @Override
    protected PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication(username, password);
    }
}

import javax.mail.*;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import java.util.Properties;

public class EmailSender {
    public static void main(String[] args) {
        String username = "your_username";
        String password = "your_password";

        // 创建Properties对象，用于配置邮件服务器
        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.host", "smtp.example.com");
        props.put("mail.smtp.port", "587");

        // 创建Session对象
        Session session = Session.getInstance(props, new MyAuthenticator(username, password));

        try {
            // 创建MimeMessage对象
            Message message = new MimeMessage(session);

            // 设置发件人
            message.setFrom(new InternetAddress("sender@example.com"));

            // 设置收件人
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("recipient@example.com"));

            // 设置邮件主题
            message.setSubject("Hello, World!");

            // 设置邮件内容
            message.setText("This is a test email.");

            // 发送邮件
            Transport.send(message);

            System.out.println("Email sent successfully.");
        } catch (MessagingException e) {
            e.printStackTrace();
        }
    }
}