I think is better to create a temporary file and set DownloadLink to delete
it after download is complete. I don't think is a good idea to let the user
download directly from the database as you proposed. See, downloads can take
some time and letting that InputStream open, might be a problem. The latency
of an external download is bigger than downloading from a local database.
Cheers,
Bruno Borges
blog.brunoborges.com.br
+55 21 76727099
"The glory of great men should always be
measured by the means they have used to
acquire it."
- Francois de La Rochefoucauld
On Fri, Oct 10, 2008 at 10:04 PM, Dane Laverty <[EMAIL PROTECTED]>wrote:
> Thank you for the advice. Here's the solution I came up with, in case
> it's useful to anyone else.
>
> First I used the DownloadLink as a template for my "blobDownloadLink".
> Then I created an InputStreamResourceStream, which is essentially a
> barely modified version of Wicket's FileResourceStream, taking an
> InputStream as the constructor parameter instead of a File. The code for
> both of those is below.
>
> While this solution works, the two issues still hanging in my mind are:
> 1. I'm sure there's an easier way to get the InputStream into an
> IResourceStream than to create an InputStreamResourceStream class...I
> just couldn't figure out what it is.
> 2. When I get the Blob from the database like this,
>
> rs.getBinaryStream(1);
>
> the returned BinaryStream doesn't work. Doing this,
>
> java.sql.Blob blob = rs.getBlob(1);
> return blob.getBinaryStream();
>
> doesn't work either. So I ended up doing,
>
> java.sql.Blob blob = rs.getBlob(1);
> byte[] bytes = new byte[(int)blob.length()];
> try {
> blob.getBinaryStream().read(bytes);
> } catch (IOException ioe) {
> // handle it
> }
> return new ByteArrayInputStream(bytes);
>
> Not pretty, but it works.
>
> *******
> // Relevant code for blobDownloadLink
>
> Link blobDownloadLink = new Link("blobDownloadLink") {
> @Override
> public void onClick() {
> InputStream inputStream =
> //getBlobAsInputStreamFromDatabase();
>
> IResourceStream resourceStream =
> new InputStreamResourceStream(inputStream);
>
> getRequestCycle().setRequestTarget(new
> ResourceStreamRequestTarget(resourceStream)
> {
> public String
> getFileName()
> {
> return
> //theFileNameYouWantAssociatedWithThisDownload;
> }
>
> public void
> respond(RequestCycle requestCycle)
> {
>
> super.respond(requestCycle);
>
> }
> });
>
> try {
> inputStream.close();
> } catch (IOException ioe) {
> logger.error("Error
> attempting to close inputStream in blobDownloadLink.", ioe);
> }
> };
> };
>
> ********
> // Relevant code for InputStreamResourceStream
>
> import java.io.IOException;
> import java.io.InputStream;
> import org.apache.wicket.util.resource.AbstractResourceStream;
> import org.apache.wicket.util.resource.ResourceStreamNotFoundException;
>
> /**
> * An InputStreamResourceStream is an IResource implementation for
> files.
> *
> * @see org.apache.wicket.util.resource.IResourceStream
> * @see org.apache.wicket.util.watch.IModifiable
> * @author Dane Laverty
> */
> public class InputStreamResourceStream extends AbstractResourceStream
> {
> private static final long serialVersionUID = 1L;
>
> /** Resource stream */
> private transient InputStream inputStream;
>
> /**
> * Constructor.
> *
> * @param inputStream
> * [EMAIL PROTECTED] InputStream} containing resource
> */
> public InputStreamResourceStream(InputStream inputStream)
> {
> this.inputStream = inputStream;
> }
>
> /**
> * Closes this resource.
> *
> * @throws IOException
> */
> public void close() throws IOException
> {
> if (inputStream != null)
> {
> inputStream.close();
> inputStream = null;
> }
> }
>
> /**
> * @see IResourceStream#getContentType()
> */
> public String getContentType()
> {
> // Let ResourceStreamRequestTarget handle content-type
> automatically
> return null;
> }
>
> /**
> * @return A readable input stream for this resource. The same
> input stream is returned until
> * <tt>InputStreamResourceStream.close()</tt> is
> invoked.
> *
> * @throws ResourceStreamNotFoundException
> */
> public InputStream getInputStream() throws
> ResourceStreamNotFoundException
> {
> if (inputStream == null)
> throw new
> ResourceStreamNotFoundException("InputStream could not be found");
>
> return inputStream;
> }
>
> }
>
>
> -----Original Message-----
> From: Igor Vaynberg [mailto:[EMAIL PROTECTED]
> Sent: Friday, October 10, 2008 3:37 PM
> To: [email protected]
> Subject: Re: Downloading a BLOB
>
> i didnt say use the downloadlink, i said see how it works...
>
> -igor
>
> On Fri, Oct 10, 2008 at 3:32 PM, Dane Laverty
> <[EMAIL PROTECTED]> wrote:
> > DownloadLink appears to accept only a file pathname. If I understand
> it
> > correctly, the only way I could use that would be to read the BLOB
> into
> > a file on the server, and then have the DownloadLink point to that
> file.
> > I believe that would require me to have the file created when the page
> > is generated, rather than when the link is clicked. Since there are
> > going to be many links on this page, I would rather be able to wait
> > until the user clicks the link to stream the BLOB to them.
> >
> > -----Original Message-----
> > From: Igor Vaynberg [mailto:[EMAIL PROTECTED]
> > Sent: Friday, October 10, 2008 3:26 PM
> > To: [email protected]
> > Subject: Re: Downloading a BLOB
> >
> > see how downloadlink works
> >
> > -igor
> >
> > On Fri, Oct 10, 2008 at 3:21 PM, Dane Laverty
> > <[EMAIL PROTECTED]> wrote:
> >> The title basically says it all. I've got a BLOB in a database, and I
> >> want the user to be able to click a link and download it. Any wicket
> >> solutions to do this? Thanks much.
> >>
> >>
> >>
> >>
> >
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