com.healthmarketscience.rmiio.RmiioUtil.java Source code

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Here is the source code for com.healthmarketscience.rmiio.RmiioUtil.java

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/*
 * Copyright (c) 2007 Health Market Science, Inc.
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License.
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 * You can contact Health Market Science at info@healthmarketscience.com
 * or at the following address:
 * Health Market Science
 * 2700 Horizon Drive
 * Suite 200
 * King of Prussia, PA 19406
 */

package com.healthmarketscience.rmiio;

import java.io.Closeable;
import java.io.IOException;
import java.util.Iterator;

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

/**
 * Utility methods for working with rmiio classes.
 * 
 * @author James Ahlborn
 */
public class RmiioUtil {
    private static final Log LOG = LogFactory.getLog(RmiioUtil.class);

    private RmiioUtil() {
    }

    /**
     * Adapts an {@link Iterator} to the {@link CloseableIOIterator} interface.
     * If the given iterator implements {@link Closeable}, it will be closed by
     * a close call on the wrapper. The wrapper implementation is a subclass of {@link AbstractCloseableIOIterator}, so the iterator will automagically
     * be closed if used with a SerialRemoteIteratorServer.
     */
    public static <T> CloseableIOIterator<T> adapt(Iterator<? extends T> iter) {
        return new IOIteratorAdapter<T>(iter);
    }

    /**
     * Closes the given Closeable if non-{@code null}, swallowing any
     * IOExceptions generated.
     */
    static void closeQuietly(Closeable closeable) {
        // yes, this has been written many times before and elsewhere, but i did
        // not want to add a dependency just for one method
        if (closeable != null) {
            try {
                closeable.close();
            } catch (IOException e) {
                // optionally log the exception, but otherwise ignore
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Failed closing closeable", e);
                }
            }
        }
    }

    /**
     * Adapts an Iterator to the CloseableIOIterator interface.
     */
    private static class IOIteratorAdapter<DataType> extends AbstractCloseableIOIterator<DataType> {
        private final Iterator<? extends DataType> _iter;

        public IOIteratorAdapter(Iterator<? extends DataType> iter) {
            _iter = iter;
        }

        public boolean hasNext() {
            return _iter.hasNext();
        }

        @Override
        protected DataType nextImpl() {
            return _iter.next();
        }

        @Override
        protected void closeImpl() {
            if (_iter instanceof Closeable) {
                closeQuietly((Closeable) _iter);
            }
        }

    }

}