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