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。

复制邮件和附件的代码对大多数文件都适用，但长文件名存在问题。

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："Copy of SKI17042 surgery CPT choices for CRLM population.xlsx" 显示在名称为 "Untitled attachment 00006.dat" 的电子邮件附件中。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，这可能是导致问题的原因。

当我在文本编辑器中打开 .eml 时，我看到带有换行符的 headers（请注意第 3/4 行和第 7/8 行中的换行符跨越文件名：

------=_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，如果您获取文件并打开 .xlsx，它会在 Excel 中打开，内容符合预期。

有没有人知道如何解决 JavaMail 中的文件附件名称问题？

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，它将按照 RFC 2231.

中的描述拆分为多个参数

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

您可以通过将属性 mail.mime.encodeparameters 设置为 false.
来禁用对 RFC 2231 编码的所有使用
您可以通过将（不幸的是未记录）属性 mail.mime.splitlongparameters 设置为 false.
来禁用长参数的拆分

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

Seems like JavaMail's MimeBodyPart.setFileName inserts a line break in the email message and causes the filename to show up as invalid

java

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