Java 7: как реализовать drag & drop в Java?

вот работа вокруг того, как я, наконец, решил проблему на данный момент.

1. если file-list-flavor не поддерживается, получите URL imap из drop-event
2. откройте соединение imap с предоставленной информацией из URL imap
3. откройте imap-store, imap-папку, поиск сообщения по UID и, наконец, получить сообщение
4. преобразовать в *.формат eml

требуются библиотеки: Apache Commons I / O и Java Mail API

следующая реализация события drop:

scrDocuments.setDropTarget(new DropTarget() {
        @Override
        public synchronized void drop(DropTargetDropEvent evt) {
            try {
                Transferable transfer = evt.getTransferable();
                if(transfer.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                    evt.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                    List objects = (List)transfer.getTransferData(DataFlavor.javaFileListFlavor);
                    for(Object object : objects) {
                        if(object instanceof File) {
                            File file = (File)object;
                            // store file ...
                        }
                    }
                } else {
                    try {
                        String url = fetchURL(evt, transfer);
                        ImapMessage eml = new ImapMessage(url);
                        File file = eml.fetchMessage();
                        // store file ...
                    } catch(Exception ex) {
                        System.err.println(ex.getMessage());
                    }
                }
            } catch(Exception ex) {
                System.err.println(ex.getMessage());
            } finally {
                evt.dropComplete(true);
            }
        }
    });

private String fetchURL(DropTargetDropEvent evt, Transferable transfer) throws IOException, UnsupportedEncodingException, UnsupportedFlavorException {
    for(DataFlavor flavor : transfer.getTransferDataFlavors()) {
        if(flavor.isRepresentationClassInputStream()) {
            if(flavor.getHumanPresentableName().equals("application/x-moz-file-promise-url")) {
                evt.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                BufferedReader reader = new BufferedReader(new InputStreamReader((InputStream)transfer.getTransferData(flavor), "ISO-8859-1"));
                String fAddress = reader.readLine();
                reader.close();
                return fAddress;
            }
        }
    }
    throw new IOException("No transferable object or stream found.");
}

и следующий класс ищет сервер imap и извлекает почту:

public class ImapMessage {

    private String authority;
    private String protocol;
    private String host;
    private int port;
    private String username;
    private String password;
    private String foldername;
    private long msgid;
    private String filename;
    private Message message;

    public ImapMessage(String url) throws IOException, MessagingException {
        parseURL(decodeURL(url));
    }

    @Override
    public String toString() {
        return "protocol: "+protocol+"\n"+
               "host: "+host+"\n"+
               "port: "+port+"\n"+
               "username: "+username+"\n"+
               "password: "+password+"\n"+
               "folder: "+foldername+"\n"+
               "msgid: "+msgid+"\n"+
               "filename: "+filename;
    }

    private String decodeURL(String url) throws IOException {
        if(url!=null && !url.isEmpty()) {
            String newurl = "";
            for(int i=0; i<url.length(); i+=2) {
                newurl+=url.substring(i, i+1);
            }
            newurl = StringUtils.replace(newurl, "%3E", ">");
            newurl = StringUtils.replace(newurl, "%20", " ");
            return newurl;
        } else {
            throw new IOException("The given URL is empty or invalid.");
        }
    }


    private void parseURL(String url) throws IOException, MalformedURLException {
        if(url!=null && !url.isEmpty()) {
            //<editor-fold defaultstate="collapsed" desc="Parse Protocol">
            if(url.startsWith("imaps")) {
                url = StringUtils.replace(url, "imaps", "http", 1);
                protocol = "imaps";
            } else if(url.startsWith("imap")) {
                url = StringUtils.replace(url, "imap", "http", 1);
                protocol = "imap";
            } else {
                throw new IOException("Unsupported protocol: "+url.substring(0, url.indexOf("://")));
            }

            try {
                URL newurl = new URL(url);
                String path = newurl.getPath();
                String query = newurl.getQuery();
                authority = newurl.getAuthority();
                host = newurl.getHost();
                port = newurl.getPort();
                username = newurl.getUserInfo();
                password = "provide your password here";
                foldername = path.substring(path.indexOf(">/")+2, path.lastIndexOf(">"));
                msgid = Long.parseLong(path.substring(path.lastIndexOf(">")+1, path.length()));
                filename = query.substring(query.indexOf("=")+1, query.length());
            } catch (MalformedURLException ex) {
                throw ex;
            }
        } else {
            throw new IOException("The given URL is empty or invalid.");
        }
    }

        public File fetchMessage() throws IOException, FileNotFoundException, MessagingException {

            Store store = null;
            Folder folder = null;
            File filepath = new File("/destination/directory");
            try {
                Properties props = System.getProperties();
                props.setProperty("mail.store.protocol", protocol);
                Session session = Session.getDefaultInstance(props, null);
                // session.setDebug(true);
                store = session.getStore(protocol);
                store.connect(host, port, username, password);
                folder = store.getFolder(foldername);
                folder.open(Folder.READ_ONLY);
                UIDFolder ufolder = (UIDFolder)folder;
                message = ufolder.getMessageByUID(msgid);
                if(message!=null) {
                    File file = null;
                    if(filename.equals("null")) {
                        file = new File(filepath.getAbsolutePath()+File.separator+Long.toString(System.nanoTime())+".eml");
                    } else {
                        file = new File(filepath.getAbsolutePath()+File.separator+filename);
                    }
                    message.writeTo(new FileOutputStream(file));
                    return file;
                } else {
                    throw new MessagingException("The requested e-mail could not be found on the mail server.");
                }
            } catch(Exception ex) {
                throw ex;
            } finally {
                if(folder!=null) {
                    folder.close(true);
                }
                if(store!=null) {
                    store.close();
                }
            }
        }

    }