Java ClassCastException javax.mail.util.SharedByteArrayInputStream无法强制转换为javax.mail.Multipart

Question

当我尝试从Linux平台上的SMTP服务器读取电子邮件时，它会攻击Multipart Class强制转换异常但它在Windows平台上正常工作。请帮助我解决Linux平台上的主要问题。感谢

Email Content Type : multipart/mixed;

Email Attachment   :  boundary="doBdxOr1WFK/0oBG/sJf8iChfky6UG3OUxjg7g=="

Exception          : javax.mail.util.SharedByteArrayInputStream cannot be cast to javax.mail.Multipart

Method Name : getContentFromMultipart 

public class ReadEmail {

private static final String CONTENT_TYPE_TEXT_PLAIN = "text/plain";
private static final String CONTENT_TYPE_TEXT_HTML = "text/html";
private static final String CONTENT_TYPE_TEXT_CALENDAR = "text/calendar";
private static final String CONTENT_TYPE_MULTIPART_ALTERNATIVE = "multipart/alternative";
private static final String CONTENT_TYPE_MULTIPART_RELATED = "multipart/related";
private static final String CONTENT_TYPE_MULTIPART_MIXED = "multipart/mixed";
private boolean plainTextEmail;
private String contentType;

private String getContent(Message msg) throws Exception {
    String emailContent = "";
    try {
        // if email content contains multiple content types/attachments
        if (msg.getContent() instanceof Multipart) {
            emailContent = this.getContentFromMultipart(msg);
        } else if (msg.getContent() instanceof String) {
            // if email content is only text based or html based
            if (msg.getContentType().contains(this.CONTENT_TYPE_TEXT_PLAIN)) {
                plainTextEmail = true;
                contentType = this.CONTENT_TYPE_TEXT_PLAIN;
                emailContent += msg.getContent().toString();
            } else if (msg.getContentType().contains(this.CONTENT_TYPE_TEXT_HTML)) {
                plainTextEmail = false;
                contentType = this.CONTENT_TYPE_TEXT_HTML;
                emailContent += msg.getContent().toString();
            }

            return emailContent;
        }
        // if email content is in the form of input string (Bain Capital
        // link based emails)
        else if (msg.getContent() instanceof InputStream) {
            logger.log(msg.getContentType());
            if (msg.getContentType().contains(this.CONTENT_TYPE_TEXT_CALENDAR)) {
                contentType = this.CONTENT_TYPE_TEXT_CALENDAR;
            }
            if (msg.getContentType().contains("multipart/mixed")) {
                contentType = "multipart/mixed"; // this.CONTENT_TYPE_MULTIPART_MIXED;
                if (msg.isMimeType("multipart/*")) {
                    emailContent += emailContent = this.getContentFromMultipart(msg, this);
                }
            }
            InputStream inputStream = (InputStream) msg.getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            StringBuilder out = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                out.append(line);
            }
            emailContent = out.toString();

            inputStream.close();
            reader.close();
        }
    } catch (Exception ex) {
        emailContent = "exception";
    }
    return emailContent;
}

private String getContentFromMultipart(Message msg) throws IOException, MessagingException {
    Object objectContent = msg.getContent();
    Multipart mp = (Multipart) objectContent;
    int count = mp.getCount();
    String emailContent = "";
    for (int i = 0; i < count; i++) {
        if (mp.getBodyPart(i).getContentType().contains(this.CONTENT_TYPE_TEXT_HTML)) {
            plainTextEmail = false;
            contentType = this.CONTENT_TYPE_TEXT_HTML;
            emailContent += mp.getBodyPart(i).getContent().toString();
        } else if (mp.getBodyPart(i).getContentType().contains(this.CONTENT_TYPE_TEXT_PLAIN)) {
            plainTextEmail = true;
            contentType = this.CONTENT_TYPE_TEXT_PLAIN;
            emailContent += mp.getBodyPart(i).getContent().toString();
        } else if (mp.getBodyPart(i).getContentType().contains(this.CONTENT_TYPE_MULTIPART_ALTERNATIVE) || mp.getBodyPart(i).getContentType().contains(this.CONTENT_TYPE_MULTIPART_RELATED)
                || mp.getBodyPart(i).getContentType().contains(this.CONTENT_TYPE_MULTIPART_MIXED)) {
            emailContent += parseMultipartEmailContent(mp.getBodyPart(i));
        }
    }
    return emailContent;
}

}