使用Java发送邮件

import javax.mail.*;
import javax.mail.internet.*;

import java.util.Properties;

public class EmailSender {
    public void sendEmail(String recipient, String subject, String messageBody) {
        //定义发送邮件的属性
        final String username = "your-email-id";
        final String password = "your-password";

        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");

        //获取Session对象
        Session session = Session.getInstance(props,
          new javax.mail.Authenticator() {
              protected PasswordAuthentication getPasswordAuthentication() {
                  return new PasswordAuthentication(username, password);
              }
          });

        try {
            //创建MimeMessage对象
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("from-email"));
            message.setRecipients(Message.RecipientType.TO,
                    InternetAddress.parse(recipient));
            message.setSubject(subject);
            message.setText(messageBody);

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

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}

public class EmailSenderWithAttachment {
    public void sendEmailWithAttachment(String recipient, String subject, String messageBody, String fileName) {
        //创建和配置Session
        //...省略相同的部分代码...

        try {
            //创建含有附件的邮件
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("from-email"));
            message.setRecipients(Message.RecipientType.TO,InternetAddress.parse(recipient));
            message.setSubject(subject);

            Multipart multipart = new MimeMultipart();
            BodyPart messageBodyPart = new MimeBodyPart();
            messageBodyPart.setText(messageBody);
            multipart.addBodyPart(messageBodyPart);

            //创建附件部分
            messageBodyPart = new MimeBodyPart();
            DataSource source = new FileDataSource(fileName);
            messageBodyPart.setDataHandler(new DataHandler(source));
            messageBodyPart.setFileName(fileName);
            multipart.addBodyPart(messageBodyPart);

            //设置邮件内容
            message.setContent(multipart);

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

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}