/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
*
* University Of Edinburgh (EDINA)
* Scotland
*
*
* File Name : AnonItemExportDownloadReader.java
* Author : Ian Fieldhouse (ianfi)
* Approver : Gareth Waller
*
* Notes :
*
*
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* HISTORY
* -------
*
* $LastChangedRevision$
* $LastChangedDate$
* $LastChangedBy$
*/
package org.dspace.app.xmlui.cocoon;
import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
import org.apache.avalon.excalibur.pool.Recyclable;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.cocoon.ProcessingException;
import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.environment.Response;
import org.apache.cocoon.environment.SourceResolver;
import org.apache.cocoon.environment.http.HttpResponse;
import org.apache.cocoon.reading.AbstractReader;
import org.apache.cocoon.util.ByteRange;
import org.dspace.app.itemexport.AnonItemExport;
import org.dspace.app.xmlui.utils.ContextUtil;
import org.dspace.core.Context;
import org.xml.sax.SAXException;
/**
* @author Ian Fieldhouse (ianfi)
*/
public class AnonItemExportDownloadReader extends AbstractReader implements
Recyclable {
/**
* How big of a buffer should we use when reading from the bitstream before
* writing to the HTTP response?
*/
protected static final int BUFFER_SIZE = 8192;
/**
* When should a download expire in milliseconds. This should be set to
* some low value just to prevent someone hitting DSpace repeatedly from
* killing the server. Note: 60000 milliseconds are in a second.
*
* Format: minutes * seconds * milliseconds
*/
protected static final int expires = 60 * 60 * 60000;
/** The Cocoon response */
protected Response response;
/** The Cocoon request */
protected Request request;
/** The bitstream file */
protected InputStream compressedExportInputStream;
/** The compressed export's reported size */
protected long compressedExportSize;
protected String compressedExportName;
/**
* Set up the export reader.
*
* See the class description for information on configuration options.
*/
public void setup(SourceResolver resolver, Map objectModel, String src,
Parameters par) throws ProcessingException, SAXException,
IOException
{
super.setup(resolver, objectModel, src, par);
try
{
this.request = ObjectModelHelper.getRequest(objectModel);
this.response = ObjectModelHelper.getResponse(objectModel);
Context context = ContextUtil.obtainContext(objectModel);
/*
* Get our parameters that identify the bitstream
*/
String fileName = par.getParameter("fileName", null);
/*
* Success, bitstream found.
* Store these for later retrieval.
*/
this.compressedExportInputStream = AnonItemExport.getExportDownloadInputStream(fileName);
this.compressedExportSize = AnonItemExport.getExportFileSize(fileName);
this.compressedExportName = fileName;
}
catch (Exception e)
{
throw new ProcessingException("Unable to read bitstream.",e);
}
}
/**
* Write the actual data out to the response.
*
* Some implementation notes,
*
* 1) We set a short expires time just in the hopes of preventing someone
* from overloading the server by clicking reload a bunch of times. I
* realize that this is nowhere near 100% effective but it may help in some
* cases and shouldn't hurt anything.
*
*/
public void generate() throws IOException, SAXException, ProcessingException
{
if (this.compressedExportInputStream == null)
return;
byte[] buffer = new byte[BUFFER_SIZE];
int length = -1;
response.setDateHeader("Expires", System.currentTimeMillis() + expires);
response.setHeader("Content-disposition","attachement; filename=" + this.compressedExportName );
/*
* Turn off partial downloads, they cause problems and are only rarely used.
* Specifically some windows PDF viewers are incapable of handling this request.
* By uncommenting the following two lines you will turn this feature back on.
*/
// response.setHeader("Accept-Ranges", "bytes");
// String ranges = request.getHeader("Range");
String ranges = null;
ByteRange byteRange = null;
if (ranges != null)
{
try
{
ranges = ranges.substring(ranges.indexOf('=') + 1);
byteRange = new ByteRange(ranges);
}
catch (NumberFormatException e)
{
byteRange = null;
if (response instanceof HttpResponse)
{
/*
* Respond with status 416 (Request range not satisfiable)
*/
((HttpResponse) response).setStatus(416);
}
}
}
if (byteRange != null)
{
String entityLength;
String entityRange;
if (this.compressedExportSize != -1)
{
entityLength = "" + this.compressedExportSize;
entityRange = byteRange.intersection(new ByteRange(0, this.compressedExportSize)).toString();
}
else
{
entityLength = "*";
entityRange = byteRange.toString();
}
response.setHeader("Content-Range", entityRange + "/" + entityLength);
if (response instanceof HttpResponse)
{
/*
* Response with status 206 (Partial content)
*/
((HttpResponse) response).setStatus(206);
}
int pos = 0;
int posEnd;
while ((length = this.compressedExportInputStream.read(buffer)) > -1)
{
posEnd = pos + length - 1;
ByteRange intersection = byteRange.intersection(new ByteRange(pos, posEnd));
if (intersection != null)
{
out.write(buffer, (int) intersection.getStart() - pos, (int) intersection.length());
}
pos += length;
}
}
else
{
response.setHeader("Content-Length", String.valueOf(this.compressedExportSize));
while ((length = this.compressedExportInputStream.read(buffer)) > -1)
{
out.write(buffer, 0, length);
}
out.flush();
}
}
/**
* Returns the mime-type of the bitstream.
*/
public String getMimeType()
{
return AnonItemExport.COMPRESSED_EXPORT_MIME_TYPE;
}
/**
* Recycle
*/
public void recycle() {
this.response = null;
this.request = null;
this.compressedExportInputStream = null;
this.compressedExportSize = 0;
}
}