gov.nij.bundles.intermediaries.ers.EntityResolutionNamespaceContextHelpers.java Source code

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Here is the source code for gov.nij.bundles.intermediaries.ers.EntityResolutionNamespaceContextHelpers.java

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/*
 * Copyright 2013 SEARCH Group, Incorporated. 
 * 
 * See the NOTICE file distributed with  this work for additional information 
 * regarding copyright ownership.  SEARCH Group Inc. 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 gov.nij.bundles.intermediaries.ers;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.w3c.dom.Node;

/**
 * This class has helper methods to assist with parsing the attribute parameters.
 * 
 */

public class EntityResolutionNamespaceContextHelpers {

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

    /**
     * 
     * This method will return a namespace map from an attribute parameter node.  Each attribute parameter
     * will have its own namespace map to facilitate xpath processing.
     * 
     * @param attributeXpathValue
     * @param node
     * @return
     * @throws Exception
     */
    public static Map<String, String> returnNamespaceMapFromNode(String attributeXpathValue, Node node)
            throws Exception {
        LOG.debug("Attribute parameter xpath value: " + attributeXpathValue);

        Map<String, String> namespaceMap = new HashMap<String, String>();

        //Get all prefixes from the xpath statement
        Set<String> prefixes = returnPrefixes(attributeXpathValue);

        //Lookup prefixes and add to namespace map
        for (String prefix : prefixes) {
            LOG.debug("Prefix returned from 'returnPrefixes' method : " + prefix);

            String namespace = node.lookupNamespaceURI(prefix);

            LOG.debug("Namespace Prefix: " + prefix + ", Namespace: " + namespace);

            namespaceMap.put(prefix, namespace);

        }

        return namespaceMap;
    }

    /**
     * This method returns all prefixes that are in an xpath expression
     * 
     * @param xpath
     * @return
     */
    public static Set<String> returnPrefixes(String xpath) {
        //Return all the strings by splitting on the regular expression that will find '/' and '//'
        //TODO: improve this regular expression, it will return empty strings in some use cases.
        String[] xpathValue = xpath.split("/|//");

        //Use a hashset for prefixes so we don't repeat namespaces
        Set<String> prefixes = new HashSet<String>();

        for (int i = 0; i < xpathValue.length; i++) {

            //Check to see if string is empty, regular expression will return empty strings in some cases
            if (StringUtils.isNotEmpty(xpathValue[i])) {
                String prefixAndElement = xpathValue[i];

                //If we have an '@', we need to get that prefix as well
                if (prefixAndElement.contains("@")) {
                    String[] prefixesFromAttributes = StringUtils.substringsBetween(prefixAndElement, "@", ":");

                    for (int j = 0; j < prefixesFromAttributes.length; j++) {
                        prefixes.add(prefixesFromAttributes[j]);
                    }

                } else {
                    //If there are no attributes, just get the namespace prefix which will appear before the ':'
                    String prefix = StringUtils.substringBefore(prefixAndElement, ":");
                    prefixes.add(prefix);
                }
            }
        }

        return prefixes;

    }
}