001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.io;
018
019import com.google.common.annotations.Beta;
020
021import java.io.Flushable;
022import java.io.IOException;
023import java.util.logging.Level;
024import java.util.logging.Logger;
025
026/**
027 * Utility methods for working with {@link Flushable} objects.
028 *
029 * @author Michael Lancaster
030 * @since 1.0
031 */
032@Beta
033public final class Flushables {
034  private static final Logger logger
035      = Logger.getLogger(Flushables.class.getName());
036
037  private Flushables() {}
038
039  /**
040   * Flush a {@link Flushable}, with control over whether an
041   * {@code IOException} may be thrown.
042   *
043   * <p>If {@code swallowIOException} is true, then we don't rethrow
044   * {@code IOException}, but merely log it.
045   *
046   * @param flushable the {@code Flushable} object to be flushed.
047   * @param swallowIOException if true, don't propagate IO exceptions
048   *     thrown by the {@code flush} method
049   * @throws IOException if {@code swallowIOException} is false and
050   *     {@link Flushable#flush} throws an {@code IOException}.
051   * @see Closeables#close
052   */
053  public static void flush(Flushable flushable, boolean swallowIOException)
054      throws IOException {
055    try {
056      flushable.flush();
057    } catch (IOException e) {
058      if (swallowIOException) {
059        logger.log(Level.WARNING,
060            "IOException thrown while flushing Flushable.", e);
061      } else {
062        throw e;
063      }
064    }
065  }
066
067  /**
068   * Equivalent to calling {@code flush(flushable, true)}, but with no
069   * {@code IOException} in the signature.
070   *
071   * @param flushable the {@code Flushable} object to be flushed.
072   */
073  public static void flushQuietly(Flushable flushable) {
074    try {
075      flush(flushable, true);
076    } catch (IOException e) {
077      logger.log(Level.SEVERE, "IOException should not have been thrown.", e);
078    }
079  }
080}