fop/src/org/apache/fop/apps/XSLTInputHandler.java

/* 
 * Copyright (C) 2001 The Apache Software Foundation. All rights reserved.
 * For details on use and redistribution please refer to the 
 * LICENSE file included with these sources."
 */


package org.apache.fop.apps;

import java.lang.reflect.*;


// Imported SAX classes
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

// Imported java.io classes
import java.io.*;

// FOP
import org.apache.fop.messaging.MessageHandler;
import org.apache.fop.tools.xslt.XSLTransform;

/**
 * XSLTInputHandler basically takes an xmlfile and transforms it with an xsltfile
 * and the resulting xsl:fo document is input for Fop.
 */

public class XSLTInputHandler extends InputHandler {

    File xmlfile, xsltfile;
    boolean useOldTransform = false;
    
    public XSLTInputHandler (File xmlfile, File xsltfile ) {
        this.xmlfile = xmlfile;
	this.xsltfile = xsltfile;
    }

    /**
      *  overwrites the method of the super class to return the xmlfile
      */
    public InputSource getInputSource () {
	if (useOldTransform) {
	    try {
		java.io.Writer writer;
		java.io.Reader reader;
		File tmpFile = null;
	 
		// create a Writer
		// the following is an ugly hack to allow processing of larger files
		// if xml file size is larger than 500 kb write the fo:file to disk
		if ((xmlfile.length()) > 500000) {
		    tmpFile = new File(xmlfile.getName()+".fo.tmp");
		    writer = new FileWriter(tmpFile);
		} else {
		    writer = new StringWriter();
		}

		XSLTransform.transform(xmlfile.getCanonicalPath(), xsltfile.getCanonicalPath(), writer);

		writer.flush();
		writer.close();

		if (tmpFile != null) {
		    reader = new FileReader(tmpFile);
		} else {
		    // create a input source containing the xsl:fo file which can be fed to Fop		    
		    reader = new StringReader(writer.toString());
		}
		return new InputSource(reader);
	    }
	    catch (Exception ex) {
		ex.printStackTrace();
		return null;
	    }
	}
	else {
	    return fileInputSource(xmlfile);
	}
	
    }

    /**
      * This looks to see if the Trax api is supported and uses that to 
      * get an XMLFilter. Otherwise, it falls back to using DOM documents 
      *
      */
    public XMLReader getParser() 
	throws FOPException
    {
	XMLReader result = null;
	try {
	    // try trax first
	    Class transformer = Class.forName("javax.xml.transform.Transformer");
	    transformer = Class.forName("org.apache.fop.apps.TraxInputHandler");
	    Class[] argTypes = 	{ File.class, File.class };
	    Method getFilterMethod = transformer.getMethod("getXMLFilter",argTypes);
	    File[] args = {xmlfile, xsltfile};
	    Object obj = getFilterMethod.invoke(null,args);
	    if (obj instanceof XMLReader) {
		result = (XMLReader)obj;
	    }
	}
	catch (ClassNotFoundException ex){
	    throw new FOPException(ex);
	}
	catch (InvocationTargetException ex) {
	    throw new FOPException(ex);
	}
	catch (IllegalAccessException ex) {
	    throw new FOPException(ex);
	}
	catch (NoSuchMethodException ex) {
	    throw new FOPException(ex);
	}
	// otherwise, use DOM documents via our XSLTransform tool class old style
	if (result == null) {
	    useOldTransform = true;
	    result = createParser();
	}
	return result;
	        
    }

 
    
}