org.broadleafcommerce.common.extensibility.context.merge.MergePoint.java Source code

Introduction

Here is the source code for org.broadleafcommerce.common.extensibility.context.merge.MergePoint.java

Source

/*
 * #%L
 * BroadleafCommerce Common Libraries
 * %%
 * Copyright (C) 2009 - 2013 Broadleaf Commerce
 * %%
 * 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.
 * #L%
 */
package org.broadleafcommerce.common.extensibility.context.merge;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.broadleafcommerce.common.extensibility.context.merge.handlers.MergeHandler;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import javax.xml.transform.TransformerException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * This class provides the xml merging apparatus at a defined XPath merge point in 
 * 2 xml documents. The MergeHandler that embodies the XPath point can have
 * embedded XPath merge points, resulting in a cumulative effect with varying
 * merge behavior for a sector of the documents. For example, it may be desirable
 * to replace all the child nodes of a given node with all the child nodes from the same
 * parent node in the patch document, with the exception of a single node. That single
 * node may instead contribute its contents in a additive fashion (rather than replace).
 * 
 * @author jfischer
 *
 */
public class MergePoint {

    private static final Log LOG = LogFactory.getLog(MergePoint.class);

    private MergeHandler handler;
    private Document doc1;
    private Document doc2;
    private XPath xPath;

    public MergePoint(MergeHandler handler, Document doc1, Document doc2) {
        this.handler = handler;
        this.doc1 = doc1;
        this.doc2 = doc2;
        XPathFactory factory = XPathFactory.newInstance();
        xPath = factory.newXPath();
    }

    /**
     * Execute the merge operation and also provide a list of nodes that have already been
     * merged. It is up to the handler implementation to respect or ignore this list.
     * 
     * @param exhaustedNodes
     * @return list of merged nodes
     * @throws XPathExpressionException
     */
    public Node[] merge(List<Node> exhaustedNodes) throws XPathExpressionException, TransformerException {
        return merge(handler, exhaustedNodes);
    }

    private Node[] merge(MergeHandler handler, List<Node> exhaustedNodes)
            throws XPathExpressionException, TransformerException {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Processing handler: " + handler.getXPath());
        }
        if (handler.getChildren() != null) {
            MergeHandler[] children = handler.getChildren();
            for (MergeHandler aChildren : children) {
                Node[] temp = merge(aChildren, exhaustedNodes);
                if (temp != null) {
                    Collections.addAll(exhaustedNodes, temp);
                }
            }
        }
        String[] xPaths = handler.getXPath().split(" ");
        List<Node> nodeList1 = new ArrayList<Node>();
        List<Node> nodeList2 = new ArrayList<Node>();
        for (String xPathVal : xPaths) {
            NodeList temp1 = (NodeList) xPath.evaluate(xPathVal, doc1, XPathConstants.NODESET);
            if (temp1 != null) {
                int length = temp1.getLength();
                for (int j = 0; j < length; j++) {
                    nodeList1.add(temp1.item(j));
                }
            }
            NodeList temp2 = (NodeList) xPath.evaluate(xPathVal, doc2, XPathConstants.NODESET);
            if (temp2 != null) {
                int length = temp2.getLength();
                for (int j = 0; j < length; j++) {
                    nodeList2.add(temp2.item(j));
                }
            }
        }
        if (nodeList1 != null && nodeList2 != null) {
            return handler.merge(nodeList1, nodeList2, exhaustedNodes);
        }
        return null;
    }
}