    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     * Closes both output streams.
    048     * <p>
    049     * If closing the main output stream throws an exception, attempt to close the branch output stream.
    050     * </p>
    051     *
    052     * <p>
    053     * If closing the main and branch output streams both throw exceptions, which exceptions is thrown by this method is
    054     * currently unspecified and subject to change.
    055     * </p>
    056     *
    057     * @throws IOException if an I/O error occurs.
    058     */
    059    @Override
    060    public void close() throws IOException {
    061        try {
    062            super.close();
    063        } finally {
    064            this.branch.close();
    065        }
    066    }
    067
    068    /**
    069     * Flushes both streams.
    070     *
    071     * @throws IOException if an I/O error occurs.
    072     */
    073    @Override
    074    public void flush() throws IOException {
    075        super.flush();
    076        this.branch.flush();
    077    }
    078
    079    /**
    080     * Writes the bytes to both streams.
    081     *
    082     * @param b the bytes to write
    083     * @throws IOException if an I/O error occurs.
    084     */
    085    @Override
    086    public synchronized void write(final byte[] b) throws IOException {
    087        super.write(b);
    088        this.branch.write(b);
    089    }
    090
    091    /**
    092     * Writes the specified bytes to both streams.
    093     *
    094     * @param b   the bytes to write
    095     * @param off The start offset
    096     * @param len The number of bytes to write
    097     * @throws IOException if an I/O error occurs.
    098     */
    099    @Override
    100    public synchronized void write(final byte[] b, final int off, final int len) throws IOException {
    101        super.write(b, off, len);
    102        this.branch.write(b, off, len);
    103    }
    104
    105    /**
    106     * Writes a byte to both streams.
    107     *
    108     * @param b the byte to write
    109     * @throws IOException if an I/O error occurs.
    110     */
    111    @Override
    112    public synchronized void write(final int b) throws IOException {
    113        super.write(b);
    114        this.branch.write(b);
    115    }
    116
    117}