Deleting a file right after a first download also has its problems,
My HP network printer/scanner does that, i can scan to an image, but
firefox displayes then that image and what ever i do then to save it
to disk, i get nothing because FF seems to want to get it again for
saving bu hp doesnt serve it anymore, i have to use IE7 for that to
get my scanned image. HP really should do more testing! And serve the
resource differently.
On 10/13/08, Bruno Borges <[EMAIL PROTECTED]> wrote:
> 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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