    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.input;
    018
    019import static org.apache.commons.io.IOUtils.EOF;
    020
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.io.OutputStream;
    024
    025/**
    026 * InputStream proxy that transparently writes a copy of all bytes read
    027 * from the proxied stream to a given OutputStream. Using {@link #skip(long)}
    028 * or {@link #mark(int)}/{@link #reset()} on the stream will result on some
    029 * bytes from the input stream being skipped or duplicated in the output
    030 * stream.
    031 * <p>
    032 * The proxied input stream is closed when the {@link #close()} method is
    033 * called on this proxy. You may configure whether the input stream closes the
    034 * output stream.
    035 * </p>
    036 *
    037 * @since 1.4
    038 * @see ObservableInputStream
    039 */
    040public class TeeInputStream extends ProxyInputStream {
    041
    042    /**
    043     * The output stream that will receive a copy of all bytes read from the
    044     * proxied input stream.
    045     */
    046    private final OutputStream branch;
    047
    048    /**
    049     * Flag for closing the associated output stream when this stream is closed.
    050     */
    051    private final boolean closeBranch;
    052
    053    /**
    054     * Constructs a TeeInputStream that proxies the given {@link InputStream}
    055     * and copies all read bytes to the given {@link OutputStream}. The given
    056     * output stream will not be closed when this stream gets closed.
    057     *
    058     * @param input input stream to be proxied
    059     * @param branch output stream that will receive a copy of all bytes read
    060     */
    061    public TeeInputStream(final InputStream input, final OutputStream branch) {
    062        this(input, branch, false);
    063    }
    064
    065    /**
    066     * Constructs a TeeInputStream that proxies the given {@link InputStream}
    067     * and copies all read bytes to the given {@link OutputStream}. The given
    068     * output stream will be closed when this stream gets closed if the
    069     * closeBranch parameter is {@code true}.
    070     *
    071     * @param input input stream to be proxied
    072     * @param branch output stream that will receive a copy of all bytes read
    073     * @param closeBranch flag for closing also the output stream when this
    074     *                    stream is closed
    075     */
    076    public TeeInputStream(
    077            final InputStream input, final OutputStream branch, final boolean closeBranch) {
    078        super(input);
    079        this.branch = branch;
    080        this.closeBranch = closeBranch;
    081    }
    082
    083    /**
    084     * Closes the proxied input stream and, if so configured, the associated
    085     * output stream. An exception thrown from one stream will not prevent
    086     * closing of the other stream.
    087     *
    088     * @throws IOException if either of the streams could not be closed
    089     */
    090    @Override
    091    public void close() throws IOException {
    092        try {
    093            super.close();
    094        } finally {
    095            if (closeBranch) {
    096                branch.close();
    097            }
    098        }
    099    }
    100
    101    /**
    102     * Reads a single byte from the proxied input stream and writes it to
    103     * the associated output stream.
    104     *
    105     * @return next byte from the stream, or -1 if the stream has ended
    106     * @throws IOException if the stream could not be read (or written)
    107     */
    108    @Override
    109    public int read() throws IOException {
    110        final int ch = super.read();
    111        if (ch != EOF) {
    112            branch.write(ch);
    113        }
    114        return ch;
    115    }
    116
    117    /**
    118     * Reads bytes from the proxied input stream and writes the read bytes
    119     * to the associated output stream.
    120     *
    121     * @param bts byte buffer
    122     * @return number of bytes read, or -1 if the stream has ended
    123     * @throws IOException if the stream could not be read (or written)
    124     */
    125    @Override
    126    public int read(final byte[] bts) throws IOException {
    127        final int n = super.read(bts);
    128        if (n != EOF) {
    129            branch.write(bts, 0, n);
    130        }
    131        return n;
    132    }
    133
    134    /**
    135     * Reads bytes from the proxied input stream and writes the read bytes
    136     * to the associated output stream.
    137     *
    138     * @param bts byte buffer
    139     * @param st start offset within the buffer
    140     * @param end maximum number of bytes to read
    141     * @return number of bytes read, or -1 if the stream has ended
    142     * @throws IOException if the stream could not be read (or written)
    143     */
    144    @Override
    145    public int read(final byte[] bts, final int st, final int end) throws IOException {
    146        final int n = super.read(bts, st, end);
    147        if (n != EOF) {
    148            branch.write(bts, st, n);
    149        }
    150        return n;
    151    }
    152
    153}