Java -向电子邮件添加附件，而不创建文件

<dependency>
    <groupId>javax.mail</groupId>
    <artifactId>javax.mail-api</artifactId>
    <version>1.6.2</version>
</dependency>
<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.2</version>
</dependency>

Properties properties = new Properties();
properties.put("mail.smtp.host", "smtp.example.com");
Session session = Session.getInstance(properties);
MimeMessage message = new MimeMessage(session);

message.setFrom(new InternetAddress("sender@example.com"));
message.setRecipient(Message.RecipientType.TO, new InternetAddress("recipient@example.com"));
message.setSubject("Email with Attachment");
message.setText("Please find the attached file.");

Multipart multipart = new MimeMultipart();

MimeBodyPart textPart = new MimeBodyPart();
textPart.setText("Please find the attached file.");
multipart.addBodyPart(textPart);

MimeBodyPart attachmentPart = new MimeBodyPart();
DataSource source = new FileDataSource("path/to/attachment");
attachmentPart.setDataHandler(new DataHandler(source));
attachmentPart.setFileName("attachment.txt");
multipart.addBodyPart(attachmentPart);

message.setContent(multipart);

Transport.send(message);