001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.output;
018
019import java.io.OutputStream;
020
021/**
022 * Proxy stream that prevents the underlying output stream from being closed.
023 * <p>
024 * This class is typically used in cases where an output stream needs to be
025 * passed to a component that wants to explicitly close the stream even if other
026 * components would still use the stream for output.
027 * </p>
028 *
029 * @since 1.4
030 */
031public class CloseShieldOutputStream extends ProxyOutputStream {
032
033    /**
034     * Constructs a proxy that shields the given output stream from being closed.
035     *
036     * @param outputStream the output stream to wrap
037     * @return the created proxy
038     * @since 2.9.0
039     */
040    public static CloseShieldOutputStream wrap(final OutputStream outputStream) {
041        return new CloseShieldOutputStream(outputStream);
042    }
043
044    /**
045     * Constructs a proxy that shields the given output stream from being closed.
046     *
047     * @param outputStream underlying output stream
048     * @deprecated Using this constructor prevents IDEs from warning if the
049     *             underlying output stream is never closed. Use
050     *             {@link #wrap(OutputStream)} instead.
051     */
052    @Deprecated
053    public CloseShieldOutputStream(final OutputStream outputStream) {
054        super(outputStream);
055    }
056
057    /**
058     * Replaces the underlying output stream with a {@link ClosedOutputStream}
059     * sentinel. The original output stream will remain open, but this proxy will
060     * appear closed.
061     */
062    @Override
063    public void close() {
064        out = ClosedOutputStream.INSTANCE;
065    }
066
067}