    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;
    023
    024/**
    025 * A decorating input stream that counts the number of bytes that have passed
    026 * through the stream so far.
    027 * <p>
    028 * A typical use case would be during debugging, to ensure that data is being
    029 * read as expected.
    030 *
    031 */
    032public class CountingInputStream extends ProxyInputStream {
    033
    034    /** The count of bytes that have passed. */
    035    private long count;
    036
    037    /**
    038     * Constructs a new CountingInputStream.
    039     *
    040     * @param in  the InputStream to delegate to
    041     */
    042    public CountingInputStream(final InputStream in) {
    043        super(in);
    044    }
    045
    046    //-----------------------------------------------------------------------
    047
    048    /**
    049     * Skips the stream over the specified number of bytes, adding the skipped
    050     * amount to the count.
    051     *
    052     * @param length  the number of bytes to skip
    053     * @return the actual number of bytes skipped
    054     * @throws IOException if an I/O error occurs
    055     * @see java.io.InputStream#skip(long)
    056     */
    057    @Override
    058    public synchronized long skip(final long length) throws IOException {
    059        final long skip = super.skip(length);
    060        this.count += skip;
    061        return skip;
    062    }
    063
    064    /**
    065     * Adds the number of read bytes to the count.
    066     *
    067     * @param n number of bytes read, or -1 if no more bytes are available
    068     * @since 2.0
    069     */
    070    @Override
    071    protected synchronized void afterRead(final int n) {
    072        if (n != EOF) {
    073            this.count += n;
    074        }
    075    }
    076
    077    //-----------------------------------------------------------------------
    078    /**
    079     * The number of bytes that have passed through this stream.
    080     * <p>
    081     * NOTE: From v1.3 this method throws an ArithmeticException if the
    082     * count is greater than can be expressed by an <code>int</code>.
    083     * See {@link #getByteCount()} for a method using a <code>long</code>.
    084     *
    085     * @return the number of bytes accumulated
    086     * @throws ArithmeticException if the byte count is too large
    087     */
    088    public int getCount() {
    089        final long result = getByteCount();
    090        if (result > Integer.MAX_VALUE) {
    091            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    092        }
    093        return (int) result;
    094    }
    095
    096    /**
    097     * Set the byte count back to 0.
    098     * <p>
    099     * NOTE: From v1.3 this method throws an ArithmeticException if the
    100     * count is greater than can be expressed by an <code>int</code>.
    101     * See {@link #resetByteCount()} for a method using a <code>long</code>.
    102     *
    103     * @return the count previous to resetting
    104     * @throws ArithmeticException if the byte count is too large
    105     */
    106    public int resetCount() {
    107        final long result = resetByteCount();
    108        if (result > Integer.MAX_VALUE) {
    109            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    110        }
    111        return (int) result;
    112    }
    113
    114    /**
    115     * The number of bytes that have passed through this stream.
    116     * <p>
    117     * NOTE: This method is an alternative for <code>getCount()</code>
    118     * and was added because that method returns an integer which will
    119     * result in incorrect count for files over 2GB.
    120     *
    121     * @return the number of bytes accumulated
    122     * @since 1.3
    123     */
    124    public synchronized long getByteCount() {
    125        return this.count;
    126    }
    127
    128    /**
    129     * Set the byte count back to 0.
    130     * <p>
    131     * NOTE: This method is an alternative for <code>resetCount()</code>
    132     * and was added because that method returns an integer which will
    133     * result in incorrect count for files over 2GB.
    134     *
    135     * @return the count previous to resetting
    136     * @since 1.3
    137     */
    138    public synchronized long resetByteCount() {
    139        final long tmp = this.count;
    140        this.count = 0;
    141        return tmp;
    142    }
    143
    144}