org.opencastproject.dictionary.regexp.DictionaryServiceImpl.java Source code

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Here is the source code for org.opencastproject.dictionary.regexp.DictionaryServiceImpl.java

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/**
 * Licensed to The Apereo Foundation under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 *
 * The Apereo Foundation licenses this file to you under the Educational
 * Community 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://opensource.org/licenses/ecl2.txt
 *
 * 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.opencastproject.dictionary.regexp;

import static org.opencastproject.util.ReadinessIndicator.ARTIFACT;
import org.opencastproject.util.ReadinessIndicator;
import org.osgi.framework.BundleContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Dictionary;
import java.util.Hashtable;
import java.util.LinkedList;
import java.io.UnsupportedEncodingException;
import org.osgi.service.cm.ManagedService;

import java.util.regex.Pattern;
import java.util.regex.Matcher;

import org.opencastproject.dictionary.api.DictionaryService;
import org.opencastproject.metadata.mpeg7.Textual;
import org.opencastproject.metadata.mpeg7.TextualImpl;

/**
 * This dictionary implementation is a dummy implementation which which will
 * just let the whole text pass through without any kind of filtering.
 */
public class DictionaryServiceImpl implements DictionaryService, ManagedService {

    /** The logging facility */
    private static final Logger logger = LoggerFactory.getLogger(DictionaryServiceImpl.class);

    public static final String PATTERN_CONFIG_KEY = "pattern";

    /* The regular expression to use for string matching */
    private String pattern = "\\w+";

    /* The compiles pattern to use for matching */
    private Pattern compilesPattern = Pattern.compile(pattern);

    public void setPattern(String p) {
        try {
            compilesPattern = Pattern.compile(p);
            pattern = p;
        } catch (RuntimeException e) {
            logger.error("Failed to compile pattern '{}'", p);
        }
    }

    public String getPattern() {
        return pattern;
    }

    /**
     * Load configuration
     */
    public synchronized void updated(Dictionary properties) {
        if (properties != null && properties.get(PATTERN_CONFIG_KEY) != null) {
            String pattern = properties.get(PATTERN_CONFIG_KEY).toString();
            /* Fix special characters */
            try {
                pattern = new String(pattern.getBytes("ISO-8859-1"), "UTF-8");
            } catch (UnsupportedEncodingException e) {
                logger.warn("Error decoding pattern string");
            }
            logger.info("Setting pattern for regexp based DictionaryService to '{}'", pattern);
            setPattern(pattern);
        }
    }

    /**
     * OSGi callback on component activation.
     *
     * @param  ctx  the bundle context
     */
    void activate(BundleContext ctx) {
        logger.info("Activating regexp based DictionaryService");
        Dictionary<String, String> properties = new Hashtable<String, String>();
        properties.put(ARTIFACT, "dictionary");
        ctx.registerService(ReadinessIndicator.class.getName(), new ReadinessIndicator(), properties);
    }

    /**
     * Filter the text according to the rules defined by the dictionary
     * implementation used. This implementation uses a regular expression to find
     * matching terms.
     *
     * @return filtered text
     **/
    @Override
    public Textual cleanUpText(String text) {

        logger.debug("Text input: {}?", text);
        LinkedList<String> words = new LinkedList<String>();
        Matcher matcher = compilesPattern.matcher(text);
        while (matcher.find()) {
            words.add(matcher.group());
        }
        String result = org.apache.commons.lang.StringUtils.join(words, " ");
        logger.debug("Resulting text: {}?", result);
        if ("".equals(result)) {
            return null;
        }
        return new TextualImpl(result);
    }

}