/* The contents of this file are subject to the license and copyright terms
* detailed in the license directory at the root of the source tree (also
* available online at http://fedora-commons.org/license/).
*/
package fedora.localservices.fop;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.URIResolver;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.stream.StreamSource;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.fop.apps.FOPException;
import org.apache.fop.apps.FOUserAgent;
import org.apache.fop.apps.Fop;
import org.apache.fop.apps.FopFactory;
import org.apache.fop.apps.MimeConstants;
/**
* Servlet for generating and serving a PDF, given the URL to an XSL-FO file.
*
* Servlet param is:
* <ul>
* <li>source: the path to a formatting object file to render
* </ul>
*/
public class FOPServlet
extends HttpServlet {
private static final long serialVersionUID = 1L;
/** Name of the parameter used for the XSL-FO file */
protected static final String FO_REQUEST_PARAM = "source";
/** Name of the parameter used for the XML file */
protected static final String XML_REQUEST_PARAM = "xml";
/** Name of the parameter used for the XSLT file */
protected static final String XSLT_REQUEST_PARAM = "xslt";
/** Logger to give to FOP */
protected Log log = null;
/** The TransformerFactory used to create Transformer instances */
protected TransformerFactory transFactory = null;
/** The FopFactory used to create Fop instances */
protected FopFactory fopFactory = null;
/** URIResolver for use by this servlet */
protected URIResolver uriResolver = null;
/**
* {@inheritDoc}
*/
@Override
public void init() throws ServletException {
this.log = LogFactory.getLog(FOPServlet.class.getName());
this.uriResolver = new RepositoryURIResolver();
this.transFactory = TransformerFactory.newInstance();
this.transFactory.setURIResolver(this.uriResolver);
//Configure FopFactory as desired
this.fopFactory = FopFactory.newInstance();
this.fopFactory.setURIResolver(this.uriResolver);
configureFopFactory();
}
/**
* This method is called right after the FopFactory is instantiated and can be overridden
* by subclasses to perform additional configuration.
*/
protected void configureFopFactory() {
//Subclass and override this method to perform additional configuration
}
/**
* {@inheritDoc}
*/
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException {
try {
// Get parameters
String foParam = request.getParameter(FO_REQUEST_PARAM);
String xmlParam = request.getParameter(XML_REQUEST_PARAM);
String xsltParam = request.getParameter(XSLT_REQUEST_PARAM);
if (foParam != null) {
renderFO(foParam, response);
} else if ((xmlParam != null) && (xsltParam != null)) {
// Note: Not current supported but may be added in a future release. DWD
//renderXML(xmlParam, xsltParam, response);
} else {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><head><title>Error</title></head>\n"
+ "<body><h1>FOPServlet Error</h1><h3>No 'source' "
+ "request param given.</body></html>");
}
} catch (Exception ex) {
throw new ServletException(ex);
}
}
/**
* Converts a String parameter to a JAXP Source object.
* @param param a String parameter
* @return Source the generated Source object
*/
protected Source convertString2Source(String param) {
Source src;
try {
src = uriResolver.resolve(param, null);
} catch (TransformerException e) {
src = null;
}
if (src == null) {
src = new StreamSource(new File(param));
}
return src;
}
private void sendPDF(byte[] content, HttpServletResponse response) throws IOException {
//Send the result back to the client
response.setContentType("application/pdf");
response.setContentLength(content.length);
response.getOutputStream().write(content);
response.getOutputStream().flush();
}
/**
* Renders an XSL-FO file into a PDF file. The PDF is written to a byte
* array that is returned as the method's result.
* @param fo the XSL-FO file
* @param response HTTP response object
* @throws FOPException If an error occurs during the rendering of the
* XSL-FO
* @throws TransformerException If an error occurs while parsing the input
* file
* @throws IOException In case of an I/O problem
*/
protected void renderFO(String fo, HttpServletResponse response)
throws FOPException, TransformerException, IOException {
//Setup source
Source foSrc = convertString2Source(fo);
//Setup the identity transformation
Transformer transformer = this.transFactory.newTransformer();
transformer.setURIResolver(this.uriResolver);
//Start transformation and rendering process
render(foSrc, transformer, response);
}
/**
* Renders an XML file into a PDF file by applying a stylesheet
* that converts the XML to XSL-FO. The PDF is written to a byte array
* that is returned as the method's result.
* @param xml the XML file
* @param xslt the XSLT file
* @param response HTTP response object
* @throws FOPException If an error occurs during the rendering of the
* XSL-FO
* @throws TransformerException If an error occurs during XSL
* transformation
* @throws IOException In case of an I/O problem
*/
protected void renderXML(String xml, String xslt, HttpServletResponse response)
throws FOPException, TransformerException, IOException {
//Setup sources
Source xmlSrc = convertString2Source(xml);
Source xsltSrc = convertString2Source(xslt);
//Setup the XSL transformation
Transformer transformer = this.transFactory.newTransformer(xsltSrc);
transformer.setURIResolver(this.uriResolver);
//Start transformation and rendering process
render(xmlSrc, transformer, response);
}
/**
* Renders an input file (XML or XSL-FO) into a PDF file. It uses the JAXP
* transformer given to optionally transform the input document to XSL-FO.
* The transformer may be an identity transformer in which case the input
* must already be XSL-FO. The PDF is written to a byte array that is
* returned as the method's result.
* @param src Input XML or XSL-FO
* @param transformer Transformer to use for optional transformation
* @param response HTTP response object
* @throws FOPException If an error occurs during the rendering of the
* XSL-FO
* @throws TransformerException If an error occurs during XSL
* transformation
* @throws IOException In case of an I/O problem
*/
protected void render(Source src, Transformer transformer, HttpServletResponse response)
throws FOPException, TransformerException, IOException {
FOUserAgent foUserAgent = getFOUserAgent();
//Setup output
ByteArrayOutputStream out = new ByteArrayOutputStream();
//Setup FOP
Fop fop = fopFactory.newFop(MimeConstants.MIME_PDF, foUserAgent, out);
//Make sure the XSL transformation's result is piped through to FOP
Result res = new SAXResult(fop.getDefaultHandler());
//Start the transformation and rendering process
transformer.transform(src, res);
//Return the result
sendPDF(out.toByteArray(), response);
}
/** @return a new FOUserAgent for FOP */
protected FOUserAgent getFOUserAgent() {
FOUserAgent userAgent = fopFactory.newFOUserAgent();
//Configure foUserAgent as desired
return userAgent;
}
}