Well, it’s been a while since I’ve done JavaMail work, but it looks like you could just repeat this code multiple times:
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
multipart.addBodyPart(messageBodyPart);
For example, you could write a method to do it:
private static void addAttachment(Multipart multipart, String filename)
{
DataSource source = new FileDataSource(filename);
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
multipart.addBodyPart(messageBodyPart);
}
Then from your main code, just call:
addAttachment(multipart, "file1.txt");
addAttachment(multipart, "file2.txt");
etc