Closeables.java

/*******************************************************************************
 * Copyright 2013 André Rouél
 * 
 * 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 net.sf.uadetector.internal.util;

import java.io.Closeable;
import java.io.IOException;

import javax.annotation.Nullable;

import net.sf.uadetector.exception.CannotCloseException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class is intended to provide utility methods to close {@link Closeable} instances.
 * 
 * @author André Rouél
 */
public final class Closeables {

    private static final Logger LOG = LoggerFactory.getLogger(Closeables.class);

    /**
     * Closes a {@link Closeable} and swallows an occurring {@link IOException} if argument {@code swallowIOException}
     * is {@code true}, otherwise the {@code IOException} will be thrown.
     * <p>
     * This method does nothing if a null reference is passed as {@code closeable}.
     * 
     * @param closeable
     *            the {@code Closeable} object to be closed, or {@code null}
     * @param swallowIOException
     *            {@code true} if an occurring {@code IOException} should be swallowed and logged or {@code false} to
     *            throw it
     * 
     * @throws IOException
     *             if the given {@code closeable} cannot be closed
     */
    public static void close(@Nullable final Closeable closeable, final boolean swallowIOException) throws IOException {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (final IOException e) {
                if (!swallowIOException) {
                    throw e;
                }
                LOG.warn(e.getLocalizedMessage(), e);
            }
        }
    }

    /**
     * Closes a {@link Closeable} and swallows an occurring {@link IOException} if argument {@code swallowIOException}
     * is {@code true}, otherwise the {@code IOException} will be converted into a runtime exception.
     * <p>
     * This method does nothing if a null reference is passed as {@code closeable}.
     * 
     * @param closeable
     *            the {@code Closeable} object to be closed, or {@code null}
     * @param swallowIOException
     *            {@code true} if an occurring {@code IOException} should be swallowed and logged or {@code false} to
     *            throw a {@code CannotCloseException}
     * 
     * @throws CannotCloseException
     *             if the given {@code closeable} cannot be closed
     */
    public static void closeAndConvert(@Nullable final Closeable closeable, final boolean swallowIOException) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (final IOException e) {
                if (!swallowIOException) {
                    throw new CannotCloseException(e.getLocalizedMessage(), e);
                }
                LOG.warn(e.getLocalizedMessage(), e);
            }
        }
    }

    /**
     * <strong>Attention:</strong> This class is not intended to create objects from it.
     */
    private Closeables() {
        // This class is not intended to create objects from it.
    }

}