关于从java程序发送电子邮件的问题

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

public class EmailSender {
    public static void main(String[] args) {
        // 配置邮件服务器连接信息
        Properties props = new Properties();
        props.put("mail.smtp.host", "smtp.example.com");
        props.put("mail.smtp.port", "587");
        props.put("mail.smtp.auth", "true");

        // 创建会话对象
        Session session = Session.getInstance(props, new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication("your_username", "your_password");
            }
        });

        try {
            // 创建邮件消息
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("sender@example.com"));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("recipient@example.com"));
            message.setSubject("Hello, World!");
            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();
        }
    }
}