Question

我正在使用JavaMail api发送电子邮件，但是当我发送带附件的电子邮件时，我想发送附件只有base64视图。这是我实现的代码，它工作正常但有时附件没有转换为base64。

private static Multipart createMultipartMixed(Email email, List<File> attachmentFiles, Context context) throws MessagingException {
Multipart multipartMixed = new MimeMultipart("mixed");

MimeBodyPart multipartAlternativeBodyPart = new MimeBodyPart();
multipartAlternativeBodyPart.setContent(createMultipartAlternative(email, context));
multipartMixed.addBodyPart(multipartAlternativeBodyPart);

for (File file : attachmentFiles) {
    MimeBodyPart attachFilePart = createAttachmentBodyPart(file, true, null);
    multipartMixed.addBodyPart(attachFilePart);
}

return multipartMixed;
}

private static MimeBodyPart createAttachmentBodyPart(File file, boolean isAttachmentDisposition, String cid)
        throws MessagingException {
MimeBodyPart attachFilePart = new MimeBodyPart();
FileDataSource fds = new FileDataSource(file.getAbsolutePath());
attachFilePart.setDataHandler(new DataHandler(fds));
try {
    attachFilePart.setFileName(MimeUtility.encodeText(fds.getName(), "UTF-8", "B"));
    if(isAttachmentDisposition) {
        attachFilePart.setDisposition(Part.ATTACHMENT);

    } else {
        attachFilePart.setDisposition(Part.INLINE);
        attachFilePart.setContentID("<" + cid + ">");
    }
} catch (UnsupportedEncodingException e) {
    LOGGER.error("UnsupportedEncodingException: " + e.getMessage());
    e.printStackTrace();
    attachFilePart.setFileName(fds.getName());
}
return attachFilePart;

}

为什么有时附件不在Mime文件的base64视图中？提前谢谢

Answer 1

JavaMail根据正文部分的实际内容选择Content-Transfer-Encoding。如果内容主要是文本，则不会使用base64。

如果有某种理由迫使它选择base64（例如，消息将由一个总是希望附件为base64编码的损坏程序处理），则可以强制选择传输编码：

attachFilePart.setHeader("Content-Transfer-Encoding", "base64");

JavaMail将附件添加到Mime主体作为base64

1 个答案: