org.ajax4jsf.resource.util.URLToStreamHelper.java Source code

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Here is the source code for org.ajax4jsf.resource.util.URLToStreamHelper.java

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/**
 * License Agreement.
 *
 *  JBoss RichFaces - Ajax4jsf Component Library
 *
 * Copyright (C) 2007  Exadel, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
 */

package org.ajax4jsf.resource.util;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Utility class to solve JAR locking issue using {@link URLConnection#setUseCaches(boolean)} method.
 * Contains one utility method that gets {@link InputStream} from {@link URL} with caching disabled.
 * 
 * Created 07.02.2008
 * @author Nick Belaevski
 * @since 3.2
 */

public final class URLToStreamHelper {

    private static final Log log = LogFactory.getLog(URLToStreamHelper.class);

    private URLToStreamHelper() {
        super();
    }

    /**
     * Returns {@link InputStream} corresponding to argument {@link URL} 
     * but with caching disabled
     * 
     * @param url {@link URL} of the resource
     * @return {@link InputStream} instance or <code>null</code>
     * @throws IOException
     */
    public static final InputStream urlToStream(URL url) throws IOException {
        if (url != null) {
            URLConnection connection = url.openConnection();
            try {
                connection.setUseCaches(false);
            } catch (IllegalArgumentException e) {
                log.error(e.getLocalizedMessage(), e);
            }

            return connection.getInputStream();
        } else {
            return null;
        }
    }

    /**
     * Variant of {@link #urlToStream(URL)} method that doesn't throw IOException, but silently ignores them
     * 
     * @param url
     * @return
     */
    public static final InputStream urlToStreamSafe(URL url) {
        try {
            return urlToStream(url);
        } catch (IOException e) {
            // do nothing
        }

        return null;
    }

}