似乎 JavaMail 的 MimeBodyPart.setFileName 在电子邮件中插入换行符并导致文件名显示为无效

Question

我们有代码可以发送到一个人的邮箱并将带有附件的电子邮件复制到文件系统。

用于复制消息和附件的代码适用于大多数文件，但文件名过长存在问题。

if (attachment instanceof FileAttachment || attachment.getIsInline()) {
    System.out.println(attachment.getName());
    String FILE_NAME = "C:path\\" + attachment.getName();
    attachment.load(FILE_NAME);

    MimeBodyPart attachmentMime = new MimeBodyPart();
    attachmentMime.setContent(new MimeMultipart(attachment.getContentType()));
    javax.activation.DataSource source = new FileDataSource(FILE_NAME);
    attachmentMime.setDataHandler(new DataHandler(source));
    attachmentMime.setFileName(attachment.getName());
    multipart.addBodyPart(attachmentMime);
} 

例如，文件名：“CRLM population.xlsx 的 SKI17042 手术 CPT 选择副本”显示在电子邮件附件中，名称为“无标题附件 00006.dat”。当我查看创建的 .eml 文件时，JavaMail 似乎在文件名中间插入了一个换行符，这可能会导致问题。

当我在文本编辑器中打开 .eml 时，我看到带有换行符的标题（注意第 3/4 和 7/8 行中跨越文件名的换行符：

------=_Part_3_840180718.1542390637623
Content-Type: application/octet-stream; 
    name*0="Copy of SKI17042 surgery CPT choices for CRLM
 population.xls"; name*1=x
Content-Transfer-Encoding: base64
Content-Disposition: attachment; 
    filename*0="Copy of SKI17042 surgery CPT choices for CRLM
 population.xls"; filename*1=x

文件内容很好，如果您将文件放在 .xlsx 上，它会在 Excel 中按预期打开内容。

有没有人有任何关于如何解决 JavaMail 中文件附件名称的问题的信息或想法？

谢谢！

编辑 - 解决方案

    Properties props = System.getProperties();

    props.put("mail.mime.splitlongparameters", false);

    Session session = Session.getInstance(props, null);

    createProjectFolder(folder);

    Message message = new MimeMessage(session);
    message.setFrom(new InternetAddress(objectJSON.getString("from"), objectJSON.getString("fromName")));
    message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(objectJSON.getString("to")));
    message.setRecipients(Message.RecipientType.CC, InternetAddress.parse(objectJSON.getString("cc")));
    message.setSubject(objectJSON.getString("subject"));
    message.setSentDate(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss a").parse(objectJSON.getString("date")));

    // create the message part 
    Multipart multipart = new MimeMultipart("mixed");
    MimeBodyPart content = new MimeBodyPart();

    // fill message
    if (objectJSON.getString("body").toLowerCase().contains("html")) {
        content.setContent( objectJSON.getString("body"), "text/html; charset=utf-8" );
    }
    else {
        content.setText(objectJSON.getString("body"), "utf-8");
    }

    multipart.addBodyPart(content);

        if (objectJSON.getInt("hasAttachment") == 1) {

            ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2010_SP2);

            service.setUrl(new URI("https://mail/ews/Exchange.asmx"));

            ExchangeCredentials credentials = new WebCredentials(developerEmail, password);

            service.setCredentials(credentials);

            try {

                EmailMessage messageWithAttachment = EmailMessage.bind(service, new ItemId(emailId));

                    AttachmentCollection attachmentsCol = messageWithAttachment.getAttachments(); 
                    System.out.println("attachments: " + attachmentsCol.getCount());
                    for (int i = 0; i < attachmentsCol.getCount(); i++) { 
                        FileAttachment attachment = (FileAttachment)attachmentsCol.getPropertyAtIndex(i); 

                        if (attachment instanceof FileAttachment || attachment.getIsInline()) {
                            System.out.println(attachment.getName());
                            String FILE_NAME = "C:\\R2D4\\eclipse-workspace\\DataLine\\WebContent\\WEB-INF\\email_attachments\\" + attachment.getName();
                            attachment.load(FILE_NAME);

                            MimeBodyPart attachmentMime = new MimeBodyPart();
                            attachmentMime.setContent(new MimeMultipart(attachment.getContentType()));
                            javax.activation.DataSource source = new FileDataSource(FILE_NAME);
                            attachmentMime.setDataHandler(new DataHandler(source));
                            attachmentMime.setFileName(attachment.getName());
                            multipart.addBodyPart(attachmentMime);

                        } 

                    }

            }
            catch(Exception e) {
                e.printStackTrace();
            }

            service.close();

        }


    // integration
    message.setContent(multipart);
    message.saveChanges();

Answer 1

如果文件名的长度超过 60 个字符，它将被拆分为多个参数，如RFC 2231 中所述。

看起来您处理消息的代码不了解如何处理 RFC 2231 编码参数。以下是可能的解决方案：

• 你可以通过设置属性禁用所有使用RFC 2231的编码mail.mime.encodeparameters来false。

• 您可以通过将（不幸的是未记录的）属性设置mail.mime.splitlongparameters为false.