我正在尝试使用以下带有zip file附件的片段发送邮件,我可以发送电子邮件,但作为 zip 文件的附件被转换为某个.bin文件。我需要设置一些属性吗?为什么 zip 文件被转换为 .bin 文件?  
Properties props = new Properties();
            props.setProperty("mail.transport.protocol", "smtp");
            props.setProperty("mail.host", "smtp.gmail.com");
            Session mailSession = Session.getDefaultInstance(props, null);
            mailSession.setDebug(true);
            Transport transport = mailSession.getTransport();
            MimeMessage message = new MimeMessage(mailSession);
            message.setSubject("HTML  mail with images");
            message.setFrom(new InternetAddress("b@gmail.com"));
            message.addRecipient(Message.RecipientType.TO,
                 new InternetAddress("a@gmail.com"));
            MimeMultipart multipart = new MimeMultipart("related");
            // first part  (the html)
            BodyPart messageBodyPart = new MimeBodyPart();
            String htmlText = "PFA Query Output.";
            messageBodyPart.setContent(htmlText, "text/html");
            // add it
            multipart.addBodyPart(messageBodyPart);
            // second part (the image)
            messageBodyPart = new MimeBodyPart();
            DataSource fds = new FileDataSource(zipFilePath);
            messageBodyPart.setDataHandler(new DataHandler(fds));
            messageBodyPart.setHeader("Content-ID","<image>");
            // add it
            multipart.addBodyPart(messageBodyPart);
            // put everything together
            message.setContent(multipart);
            transport.connect();
            transport.sendMessage(message,
                message.getRecipients(Message.RecipientType.TO));
            transport.close();