dependencymanager/samples.annotation/src/main/java/org/apache/felix/dm/samples/annotation/DictionaryAspect.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.felix.dm.samples.annotation;

import java.util.Dictionary;
import java.util.concurrent.CopyOnWriteArrayList;

import org.apache.felix.dm.annotation.api.AspectService;
import org.apache.felix.dm.annotation.api.PropertyMetaData;
import org.apache.felix.dm.annotation.api.ConfigurationDependency;
import org.apache.felix.dm.annotation.api.ServiceDependency;
import org.apache.felix.dm.annotation.api.Start;
import org.osgi.service.log.LogService;

/**
 * This aspect applies to the English DictionaryService, and allows to decorate it with some
 * custom English words, which are configurable from WebConsole.
 */
@AspectService(ranking = 10, filter = "(lang=en)")
public class DictionaryAspect implements DictionaryService
{
    /**
     * This is the service this aspect is applying to.
     */
    private volatile DictionaryService m_originalDictionary;

    /**
     * We store all configured words in a thread-safe data structure, because ConfigAdmin may
     * invoke our updated method at any time.
     */
    private CopyOnWriteArrayList<String> m_words = new CopyOnWriteArrayList<String>();

    /**
     * We'll use the OSGi log service for logging. If no log service is available, then we'll
     * use a NullObject.
     */
    @ServiceDependency(required = false)
    private LogService m_log;

    /**
     * Defines a configuration dependency for retrieving our english custom words (by default,
     * our PID is our full class name).
     */
    @ConfigurationDependency(
        pid="DictionaryAspectPID",
        propagate = false, 
        heading = "Aspect Dictionary",
        description = "Declare here some additional english words", 
        metadata = { 
            @PropertyMetaData(heading = "Dictionary aspect words", 
                              description = "Declare here the list of english words to be added into the default english dictionary",
                              defaults = { "aspect" }, 
                              id = "words", 
                              cardinality = Integer.MAX_VALUE) 
        }
    )
    protected void updated(Dictionary<String, ?> config)
    {
        m_words.clear();
        String[] words = (String[]) config.get("words");
        for (String word : words)
        {
            m_words.add(word);
        }
    }

    /**
     * Our Aspect Service is starting and is about to be registered in the OSGi regsitry.
     */
    @Start
    protected void start()
    {
        m_log.log(LogService.LOG_INFO, "Starting aspect Dictionary with words: " + m_words
                + "; original dictionary service=" + m_originalDictionary);
    }

    /**
     * Checks if a word is found from our custom word list. if not, delegate to the decorated
     * dictionary.
     */
    public boolean checkWord(String word)
    {
        m_log.log(LogService.LOG_INFO, "DictionaryAspect: checking word " + word
                + " (original dictionary=" + m_originalDictionary + ")");
        if (m_words.contains(word))
        {
            return true;
        }
        return m_originalDictionary.checkWord(word);
    }

    public String toString()
    {
        return "DictionaryAspect: words=" + m_words + "; original dictionary="
                + m_originalDictionary;
    }
}