Java-下载文件后从剪贴板粘贴文件

Question

I have some trouble with the Windows Explorer.

My Application starts the download of a file and puts it into the system clipboard meanwhile. If the User now pastes the file at some place of the Windows Explorer, the file isn't having its real size, but the size depending on the progress of the download.

Does somebody have an idea of how I could advise the Explorer to wait until the download has finished and copy the file to the target directory afterwards?

I also tried to "tunnel" the file over the loopback Interface using the local SMB server but it didnt help unfortunately...

Thanks in advance

Downloading the file and calling the paste to clipboard method:

new Thread(new Runnable() {

            @Override
            public void run() {

                final String where = getText();

                int selectedRows[] = CustomJTableModel.table.getSelectedRows();

                List<File> fileList = new ArrayList<File>();

                for( int i=0; selectedRows.length>i; i++ ) {

                    // Build the relative file/folder path

                    String fileName = (String)table.getValueAt(table.getSelectedRow(), 0);

                    final String value = buildPath(where, fileName);

                    new Thread(new Runnable() {

                        @Override
                        public void run() {

                            staticNetworkDaemon.getFile(value, where);

                        }

                    }).start();

                    fileList.add(new File("\\\\127.0.0.1\\r$\\downloaded" + value.replace("/", "\\")));

                }

                setClipboardFile(fileList);

            }

        }).start();

Copying the file to the clipboard:

public static void setClipboardFile(final List<File> files) {

    Transferable trans = new Transferable() {

        List<File> fileList = new ArrayList<File>();

        public DataFlavor[] getTransferDataFlavors() {

            for( File f: files ) {

                fileList.add(f);

            }

            return new DataFlavor[] { DataFlavor.javaFileListFlavor };

        }

        public boolean isDataFlavorSupported(DataFlavor flavor) {

            return DataFlavor.javaFileListFlavor.equals(flavor);

        }   

        public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {

            if (isDataFlavorSupported(flavor))

                return fileList;

            throw new UnsupportedFlavorException(flavor);

        }

    };

    Toolkit.getDefaultToolkit().getSystemClipboard().setContents(trans, null);

}

Answer 1

What you're doing is simply wrong. Don't put something in the clipboard unless it's ready to be pasted -- you're breaking the contract that you should be following when using the clipboard.

Answer 2

Maybe my answer is a little bit simplistic, but why not simply wait until the file is completely downloaded before setting it in the clipboard? What about using something like a Future to wait for it, then set it in the clipboard.

Answer 3

This...

fileList.add(new File("\\\\127.0.0.1\\r$\\downloaded" + value.replace("/", "\\")))

Is so wrong as to be mind boggling. You only want to add the where to the fileList but only AFTER it has been successfully downloaded.

Once the file has been downloaded, only then do you want to add it to the clipboard.

The creation of your Transferable is also a "little" troubling, the Transferable should make a copy of the File List the moment it is created, this prevents the List from been modified before it is used, which could change the results

Answer 4

In languages like C++ or Delphi it is possible to put to clipboard IDataObject object. IDataObject object can contain absolutely different formats. If your can paste IDataObject with CFSTR_FILEDESCRIPTOR and CFSTR_FILECONTENTS formats to clipboard your problem will be solved.

When shell requests files from clipboard it checks for CF_HDROP, CF_IDLIST, CF_FILEDESCRIPTORW/CF_FILEDESCRIPTORA or CF_FILENAMEW/CF_FILENAMEA formats. And if clipboard contains CF_FILEDESCRIPTOR format only shell will use this format for file transfer.

CF_FILEDESCRIPTOR format contains names, attributes and dates of files. CF_FILECONTENTS format contains IStream of file. And you are absolutely free to create any implementation of IStream object. When shell call IStream.Read and request the part of file which is already downloaded just return this part of file. But when shell call IStream.Read and request the part of file which is not downloaded yet - just wait and after the part is downloaded return it.