java - 电子邮件附加中文内容在电子邮件中显示问号

Question

电子邮件主题正在转换为中文，但文件中附加的电子邮件内容未转换为中文或日文，显示为???????。有人可以帮助我吗？下面是我的代码：

  MimeMessage localMsg = null;
  Properties localProp = null;
  MimeBodyPart localMimeBodyPart = null;
  Multipart localMultipart = null;
  MimeMessage localMsg = null;
  DataSource localDs = null;

   Session localSession = Session.getDefaultInstance(localProp, null);
   localMsg = new MimeMessage(localSession);

  localMsg.setHeader("Content-Type", "text/html;charset=utf-8");
  localMsg.setSubject(subjectArg, "UTF-8"); 


            localMimeBodyPart = new MimeBodyPart();

            localMimeBodyPart.setContent(bodyMsgArg, "text/html;charset=utf-8");

            localMultipart = new MimeMultipart();
            localMultipart.addBodyPart(localMimeBodyPart);

            for (int localInt1 = 0; localInt1 < attachmentsArg.length; localInt1++)
            {
                if ((attachmentsArg[localInt1] != null))
                {
                    localMimeBodyPart = new MimeBodyPart();

                    localDs = attachmentsArg[localInt1];

                    localMimeBodyPart.setDataHandler(new DataHandler( localDs));
                    localMimeBodyPart.setFileName(localDs.getName());
                    localMultipart.addBodyPart(localMimeBodyPart);

                }
            }

            localMsg.setContent(localMultipart);


        localMsg.setSentDate(new Date());

        localMsg.saveChanges();

        Transport.send(localMsg);