Java Mail POST消息正文

Question

我正在尝试阅读电子邮件，将电子邮件另存为对象，保存其附件，然后将对象作为JSON发布到API。一切正常，只是主体只输出为com.sun.mail.util.BASE64DecoderStream@1q9q9qj4。我认为代码会处理带附件的邮件正文，但它似乎不起作用。

public class ReadEmails {
    private static String saveDirectory = "C://attachments"; 

    public void setSaveDirectory(String dir) {
        ReadEmails.saveDirectory = dir;
    }

    public static void downloadEmailAttachments(String host, String port, String userName, String password) {
        Properties properties = new Properties();

        properties.put("mail.pop3.host", host);
        properties.put("mail.pop3.port", port);
        properties.put("mail.pop3.starttls.enable", "true");
        properties.put("mail.pop3.ssl.trust", host);
        properties.setProperty("mail.pop3.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        properties.setProperty("mail.pop3.socketFactory.fallback", "true");
        properties.setProperty("mail.pop3.socketFactory.port", String.valueOf(port));

        Session session = Session.getDefaultInstance(properties);

        try {
            Store store = session.getStore("pop3");
            store.connect(userName, password);

            Folder folderInbox = store.getFolder("INBOX");
            folderInbox.open(Folder.READ_ONLY);

            Message[] arrayMessages = folderInbox.getMessages();

            for (int i = 0; i < arrayMessages.length; i++) {
                Message message = arrayMessages[i];
                Address[] fromAddress = message.getFrom();
                String from = fromAddress[0].toString();
                String subject = message.getSubject();
                String sentDate = message.getSentDate().toString();

                String contentType = message.getContentType();
                String messageContent = "";

                String attachFiles = "";

                if (contentType.contains("multipart")) {
                    // content may contain attachments
                    Multipart multiPart = (Multipart) message.getContent();
                    int numberOfParts = multiPart.getCount();
                    for (int partCount = 0; partCount < numberOfParts; partCount++) {
                        MimeBodyPart part = (MimeBodyPart) multiPart.getBodyPart(partCount);
                        if (Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) {
                            // this part is attachment
                            String fileName = part.getFileName();
                            attachFiles += fileName + ", ";
                            part.saveFile(saveDirectory + File.separator + fileName);
                        } else {
                            // this part may be the message content
                            messageContent = part.getContent().toString();
                        }
                    }

                    if (attachFiles.length() > 1) {
                        attachFiles = attachFiles.substring(0, attachFiles.length() - 2);
                    }
                } else if (contentType.contains("text/plain") || contentType.contains("text/html")) {
                    Object content = message.getContent();
                    if (content != null) {
                        messageContent = content.toString();
                    }
                }


                NewCase nc = new NewCase();
                nc.setTitle(subject);
                nc.setDescription(messageContent);
                nc.setEmail(from);

                sendEmails(nc);
                System.out.print("email: "+ nc.getTitle() + nc.getDescription() + nc.getEmail());
            }

            folderInbox.close(false);
            store.close();
        } catch (NoSuchProviderException ex) {
            System.out.println("No provider for pop3.");
            ex.printStackTrace();
            System.out.println(ex);;
        } catch (MessagingException ex) {
            System.out.println("Could not connect to the message store");
            ex.printStackTrace();
            System.out.println(ex);;
        } catch (IOException ex) {
            ex.printStackTrace();
            System.out.println(ex);;
        }
    }
    static void sendEmails(NewCase nc) {
        final String url = "http://localhost:8080/email";

        String title = nc.getTitle();
        String description = nc.getDescription();
        String email = nc.getEmail();

        HttpClient httpClient = HttpClientBuilder.create().build();     
            HttpPost p = new HttpPost(url);        

            p.setEntity(new StringEntity("{\"title\":\"" + title + "\",\"description\":\"" + description + "\",\"email\":\""+ email +"\"}", 
                             ContentType.create("application/json")));

            try {
                HttpResponse r = httpClient.execute(p);
                System.out.println(r.getStatusLine().getStatusCode());

            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
}