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.IOException;
020import java.io.OutputStream;
021
022/**
023 * Classic splitter of {@link OutputStream}. Named after the Unix 'tee' command. It allows a stream to be branched off
024 * so there are now two streams.
025 */
026public class TeeOutputStream extends ProxyOutputStream {
027
028    /**
029     * The second OutputStream to write to.
030     *
031     * TODO Make private and final in 3.0.
032     */
033    protected OutputStream branch;
034
035    /**
036     * Constructs a TeeOutputStream.
037     *
038     * @param out    the main OutputStream
039     * @param branch the second OutputStream
040     */
041    public TeeOutputStream(final OutputStream out, final OutputStream branch) {
042        super(out);
043        this.branch = branch;
044    }
045
046    /**
047     * Writes the bytes to both streams.
048     *
049     * @param b the bytes to write
050     * @throws IOException if an I/O error occurs.
051     */
052    @Override
053    public synchronized void write(final byte[] b) throws IOException {
054        super.write(b);
055        this.branch.write(b);
056    }
057
058    /**
059     * Writes the specified bytes to both streams.
060     *
061     * @param b   the bytes to write
062     * @param off The start offset
063     * @param len The number of bytes to write
064     * @throws IOException if an I/O error occurs.
065     */
066    @Override
067    public synchronized void write(final byte[] b, final int off, final int len) throws IOException {
068        super.write(b, off, len);
069        this.branch.write(b, off, len);
070    }
071
072    /**
073     * Writes a byte to both streams.
074     *
075     * @param b the byte to write
076     * @throws IOException if an I/O error occurs.
077     */
078    @Override
079    public synchronized void write(final int b) throws IOException {
080        super.write(b);
081        this.branch.write(b);
082    }
083
084    /**
085     * Flushes both streams.
086     *
087     * @throws IOException if an I/O error occurs.
088     */
089    @Override
090    public void flush() throws IOException {
091        super.flush();
092        this.branch.flush();
093    }
094
095    /**
096     * Closes both output streams.
097     * <p>
098     * If closing the main output stream throws an exception, attempt to close the branch output stream.
099     * </p>
100     *
101     * <p>
102     * If closing the main and branch output streams both throw exceptions, which exceptions is thrown by this method is
103     * currently unspecified and subject to change.
104     * </p>
105     *
106     * @throws IOException if an I/O error occurs.
107     */
108    @Override
109    public void close() throws IOException {
110        try {
111            super.close();
112        } finally {
113            this.branch.close();
114        }
115    }
116
117}