/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id$ */
package org.apache.fop.servlet;
import java.io.ByteArrayOutputStream;
import java.io.File;
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.sax.SAXResult;
import javax.xml.transform.stream.StreamSource;
import org.apache.commons.logging.impl.SimpleLog;
//FOP
import org.apache.fop.apps.Fop;
import org.apache.fop.apps.FOPException;
/**
* Example servlet to generate a PDF from a servlet.
*
* Servlet param is:
*
* - fo: the path to a XSL-FO file to render
*
* or
*
* - xml: the path to an XML file to render
* - xslt: the path to an XSLT file that can transform the above XML to XSL-FO
*
*
* Example URL: http://servername/fop/servlet/FopServlet?fo=readme.fo
*
* Example URL: http://servername/fop/servlet/FopServlet?xml=data.xml&xslt=format.xsl
*
* For this to work with Internet Explorer, you might need to append "&ext=.pdf"
* to the URL.
*
* @author Apache XML FOP Development Team
* @version $Id: FopServlet.java,v 1.2 2003/03/07 09:48:05 jeremias Exp $
* (todo) Ev. add caching mechanism for Templates objects
*/
public class FopServlet extends HttpServlet {
/** Name of the parameter used for the XSL-FO file */
protected static final String FO_REQUEST_PARAM = "fo";
/** 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 SimpleLog log = null;
/** The TransformerFactory to use to create Transformer instances */
protected TransformerFactory transFactory = null;
/**
* @see javax.servlet.GenericServlet#init()
*/
public void init() throws ServletException {
this.log = new SimpleLog("FOP/Servlet");
log.setLevel(SimpleLog.LOG_LEVEL_WARN);
this.transFactory = TransformerFactory.newInstance();
}
/**
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest, HttpServletResponse)
*/
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);
//Analyze parameters and decide with method to use
byte[] content = null;
if (foParam != null) {
content = renderFO(foParam);
} else if ((xmlParam != null) && (xsltParam != null)) {
content = renderXML(xmlParam, xsltParam);
} else {
PrintWriter out = response.getWriter();
out.println("Error\n"
+ "FopServlet Error
No 'fo' "
+ "request param given.");
}
if (content != null) {
//Send the result back to the client
response.setContentType("application/pdf");
response.setContentLength(content.length);
response.getOutputStream().write(content);
response.getOutputStream().flush();
}
} 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) {
return new StreamSource(new File(param));
}
/**
* 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
* @return byte[] the rendered PDF file
* @throws FOPException If an error occurs during the rendering of the
* XSL-FO
* @throws TransformerException If an error occurs while parsing the input
* file
*/
protected byte[] renderFO(String fo)
throws FOPException, TransformerException {
//Setup source
Source foSrc = convertString2Source(fo);
//Setup the identity transformation
Transformer transformer = this.transFactory.newTransformer();
//Start transformation and rendering process
return render(foSrc, transformer);
}
/**
* 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
* @return byte[] the rendered PDF file
* @throws FOPException If an error occurs during the rendering of the
* XSL-FO
* @throws TransformerException If an error occurs during XSL
* transformation
*/
protected byte[] renderXML(String xml, String xslt)
throws FOPException, TransformerException {
//Setup sources
Source xmlSrc = convertString2Source(xml);
Source xsltSrc = convertString2Source(xslt);
//Setup the XSL transformation
Transformer transformer = this.transFactory.newTransformer(xsltSrc);
//Start transformation and rendering process
return render(xmlSrc, transformer);
}
/**
* 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
* @return byte[] the rendered PDF file
* @throws FOPException If an error occurs during the rendering of the
* XSL-FO
* @throws TransformerException If an error occurs during XSL
* transformation
*/
protected byte[] render(Source src, Transformer transformer)
throws FOPException, TransformerException {
//Setup FOP
Fop fop = new Fop(Fop.RENDER_PDF);
//Setup output
ByteArrayOutputStream out = new ByteArrayOutputStream();
fop.setOutputStream(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
return out.toByteArray();
}
}