使用JavaMail阅读阿拉伯语附件

Question

我有使用java邮件下载阿拉伯文附件的问题.

文件名始终不明确.

问题是将Bodypart附件检索为非UTF-8字符.

private void getAttachments(Message temp) throws IOException, MessagingException {
    List<File> attachments = new ArrayList<File>();

    Multipart multipart = (Multipart) temp.getContent();

    System.out.println(multipart.getCount());

    for (int i = 0; i < multipart.getCount(); i++) {
        BodyPart bodyPart = multipart.getBodyPart(i);
        if (!Part.ATTACHMENT.equalsIgnoreCase(bodyPart.getDisposition())) {
            continue; // dealing with attachments only
        }
        InputStream is = bodyPart.getInputStream();

        // getFilename always have wrong characters set 
        byte [] fileBytes = bodyPart.getFileName().toString().getBytes();

        String filename = new String(fileBytes, "UTF-8");            

        File f = new File("C:\\Attachments\\" + filename);

         System.out.println(f .getName());

         try {
        if (f == null) {
            //filename = File.createTempFile("VSX", ".out").getName();
            return;
        }

        FileOutputStream fos = new FileOutputStream(f );
        BufferedOutputStream bos = new BufferedOutputStream(fos);
        BufferedInputStream bis = new BufferedInputStream(is);

        int aByte;
        while ((aByte = bis.read()) >=0) {
            bos.write(aByte);
        }

        fos.flush();
        bos.flush();
        bos.close();
        bis.close();
        fos.close();
    } // end of try()
    catch (IOException exp) {
        System.out.println("IOException:" + exp);
    }        

        attachments.add(f);
    }
}

Answer 1

头部根据RFC 2047(它的encoded-word)中描述的机制进行编码,该机制表示匹配=?<encoding> ?B?<encoded-bytes>的头部分?=是字节编码部分.所述<编码>说如何解释的字节数,和(因为它是B风格,而不是Q样式)的<编码字节>是base-64编码.

这一切都相当复杂.幸运的是,您可以使用静态javax.mail.internet.MimeUtility.decodeText()方法轻松处理此问题.这意味着您可以切换到:

String filename = MimeUtility.decodeText(bodyPart.getFileName());

实际上,你最好将它与下一行结合起来:

File f = new File("C:\\Attachments",
                  MimeUtility.decodeText(bodyPart.getFileName()));

它更好,因为它避免了构建文件名的麻烦,而不是手动完成所有操作.(这也意味着您可以将该文字路径名分解为某个配置位置.)