org.ops4j.pax.runner.handler.internal.URLStreamHandlerExtender.java Source code

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Here is the source code for org.ops4j.pax.runner.handler.internal.URLStreamHandlerExtender.java

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/*
 * Copyright 2007 Alin Dreghiciu.
 *
 * 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.
 */
package org.ops4j.pax.runner.handler.internal;

import java.net.URLStreamHandler;
import java.net.URLStreamHandlerFactory;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.osgi.service.url.URLStreamHandlerService;
import org.ops4j.lang.NullArgumentException;

/**
 * An extender that implements URLStreamHandlerFactory.
 * Registers/unregisters URLStreamHandlerService as URLStreamHandler's.
 * Note that this is not full proven URL Handler Service implementation. It does just enough to be used in runner.
 *
 * @author Alin Dreghiciu
 * @see java.net.URLStreamHandlerFactory
 * @since August 28, 2007
 */
public class URLStreamHandlerExtender implements URLStreamHandlerFactory {

    /**
     * Logger.
     */
    private static final Log LOGGER = LogFactory.getLog(Activator.class);
    /**
     * Map between protocol and URLStreamHandlerService proxy.
     */
    private final Map<String, URLStreamHandlerProxy> m_proxies;

    /**
     * Creates a new extender.
     */
    public URLStreamHandlerExtender() {
        m_proxies = new HashMap<String, URLStreamHandlerProxy>();
    }

    /**
     * Registres itself to URL as URLStreamHandlerFactory.
     * This is not in the constructor as only once per JVM this could be set so we could not do unit tests.
     */
    public void start() {
        URLUtils.setURLStreamHandlerFactory(this);
    }

    /**
     * Registres the URLStreamHandlerService as URLStreamHandler.
     *
     * @param protocols               an array of protocols handled by URLStreamHandlerService
     * @param urlStreamHandlerService an  URLStreamHandlerService
     */
    public void register(final String[] protocols, final URLStreamHandlerService urlStreamHandlerService) {
        LOGGER.debug("Registering protocols [" + Arrays.toString(protocols) + "] to service ["
                + urlStreamHandlerService + "]");
        NullArgumentException.validateNotEmptyContent(protocols, true, "Protocol");
        NullArgumentException.validateNotNull(urlStreamHandlerService, "URL stream handler service");
        for (String protocol : protocols) {
            m_proxies.put(protocol, createProxy(urlStreamHandlerService));
        }

    }

    /**
     * Unregistres the URLStreamHandlerService as URLStreamHandler.
     *
     * @param protocols an array of protocols handled by URLStreamHandlerService
     */
    public void unregister(final String[] protocols) {
        LOGGER.debug("Unregistering protocols [" + Arrays.toString(protocols) + "]");
        NullArgumentException.validateNotEmptyContent(protocols, true, "Protocols");
        for (String protocol : protocols) {
            m_proxies.remove(protocol);
        }
    }

    /**
     * If there is a registred URLStreamHandlerService for the protocol the URLStreamHandlerService is returned,
     * otherwise will return null, so the JVM will handle as defaut.
     *
     * @see java.net.URLStreamHandlerFactory#createURLStreamHandler(String)
     */
    public URLStreamHandler createURLStreamHandler(final String protocol) {
        NullArgumentException.validateNotEmpty(protocol, true, "Protocol");
        return m_proxies.get(protocol);
    }

    /**
     * URLStreamHandlerProxy factory method.
     *
     * @param urlStreamHandlerService an URLStreamHandlerService
     *
     * @return a proxy
     */
    URLStreamHandlerProxy createProxy(final URLStreamHandlerService urlStreamHandlerService) {
        return new URLStreamHandlerProxy(urlStreamHandlerService);
    }

}