RELEASE_2_1_13/src/java/org/apache/cocoon/transformation/WriteDOMSessionTransformer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
package org.apache.cocoon.transformation;

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.Session;
import org.apache.cocoon.environment.SourceResolver;
import org.apache.cocoon.xml.dom.DOMBuilder;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * @cocoon.sitemap.component.documentation
 * Make a DOM object from SAX events and write it to the session.
 * 
 * @cocoon.sitemap.component.name   writeDOMsession
 * @cocoon.sitemap.component.logger sitemap.transformer.writeDOMsession
 * 
 * Make a DOM object from SAX events and write it to the session.
 *
 * Usage in sitemap:
 *    <map:transform type="writeDOMsession">
 *      <map:parameter name="dom-name" value="content"/>
 *      <map:parameter name="dom-root-element" value="companies"/>
 *    </map:transform>
 *
 * Where:
 *   dom-name is the name for the DOM object in the session
 *   dom-root-element is the trigger that will be the root element of the DOM
 *
 * @author <a href="mailto:sven.beauprez@the-ecorp.com">Sven Beauprez</a>
 * @version CVS $Id$
 */
public class WriteDOMSessionTransformer extends AbstractTransformer {

    public static final String DOM_NAME = "dom-name";
    public static final String DOM_ROOT_ELEMENT = "dom-root-element";

    private boolean buildDom = false;
    /**
     * component was correctly setup
     */
    private boolean setup = false;

    private Session session;
    private DOMBuilder builder;

    private String DOMName;
    private String rootElement;
    private Map storedPrefixMap;

    /**
     * Recyclable
     */
    public void recycle() {
        super.recycle();
        this.session = null;
        this.builder = null;
        this.buildDom = false;
        this.setup = false;
    }

    /* BEGIN SitemapComponent methods */

    public void setup(SourceResolver resolver, Map objectModel,
                      String source, Parameters parameters)
    throws ProcessingException, SAXException, IOException {
        getLogger().debug("WriteSessionTransformer: setup");
        Request request = ObjectModelHelper.getRequest(objectModel);
        session = request.getSession(false);
        if (session != null) {
            DOMName = parameters.getParameter(WriteDOMSessionTransformer.DOM_NAME, null);
            rootElement = parameters.getParameter(WriteDOMSessionTransformer.DOM_ROOT_ELEMENT, null);
            if (DOMName != null && rootElement != null) {
                // only now we know it is useful to store something in the session
                getLogger().debug("WriteSessionTransformer: " + WriteDOMSessionTransformer.DOM_NAME + "=" +
                                  DOMName + "; " + WriteDOMSessionTransformer.DOM_ROOT_ELEMENT + "=" +
                                  rootElement);
                setup = true;
                storedPrefixMap = new HashMap();
            } else {
                getLogger().error("WriteSessionTransformer: need " + WriteDOMSessionTransformer.DOM_NAME +
                                  " and " + WriteDOMSessionTransformer.DOM_ROOT_ELEMENT + " parameters");
            }
        } else {
            getLogger().error("WriteSessionTransformer: no session object");
        }
    }

    /* END SitemapComponent methods */

    /* BEGIN SAX ContentHandler handlers */

    public void startPrefixMapping(String prefix, String uri)
    throws SAXException {
        super.startPrefixMapping(prefix, uri);
        if (buildDom) {
            builder.startPrefixMapping(prefix, uri);
        } else if (setup) {
            storePrefixMapping(prefix, uri);
        }
    }

    public void startElement(String uri, String name, String raw, Attributes attributes)
    throws SAXException {
        // only build the DOM tree if session is available
        if (setup && name.equalsIgnoreCase(rootElement)) {
            getLogger().debug("WriteSessionTransformer: start building DOM tree");
            buildDom = true;
            builder = new DOMBuilder();
            builder.startDocument();
            launchStoredMappings();
            builder.startElement(uri, name, raw, attributes);
        } else if (buildDom) {
            builder.startElement(uri, name, raw, attributes);
        }
        super.contentHandler.startElement(uri, name, raw, attributes);
    }

    public void endElement(String uri, String name, String raw)
            throws SAXException {
        if (setup && name.equalsIgnoreCase(rootElement)) {
            buildDom = false;
            builder.endElement(uri, name, raw);
            builder.endDocument();
            getLogger().debug("WriteSessionTransformer: putting DOM tree in session object");
            session.setAttribute(DOMName, builder.getDocument().getFirstChild());
            getLogger().debug("WriteSessionTransformer: DOM tree is in session object");
        } else if (buildDom) {
            builder.endElement(uri, name, raw);
        }
        super.contentHandler.endElement(uri, name, raw);
    }

    public void characters(char c[], int start, int len) throws SAXException {
        if (buildDom) {
            builder.characters(c, start, len);
        }
        super.contentHandler.characters(c, start, len);
    }

    public void startCDATA() throws SAXException {
        if (buildDom) {
            builder.startCDATA();
        }
        super.lexicalHandler.startCDATA();
    }

    public void endCDATA() throws SAXException {
        if (buildDom) {
            builder.endCDATA();
        }
        super.lexicalHandler.endCDATA();
    }

    /* END SAX ContentHandler handlers */

    protected void storePrefixMapping(String prefix, String uri) {
        storedPrefixMap.put(prefix, uri);
    }

    protected void launchStoredMappings() throws SAXException {
        Iterator it = storedPrefixMap.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            String pre = (String) entry.getKey();
            String uri = (String) entry.getValue();
            getLogger().debug("WriteSessionTransformer: launching prefix mapping[ pre: " + pre + " uri: " + uri + " ]");
            builder.startPrefixMapping(pre, uri);
        }
    }

}