    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.OutputStream;
    020
    021/**
    022 * A decorating output stream that counts the number of bytes that have passed
    023 * through the stream so far.
    024 * <p>
    025 * A typical use case would be during debugging, to ensure that data is being
    026 * written as expected.
    027 *
    028 */
    029public class CountingOutputStream extends ProxyOutputStream {
    030
    031    /** The count of bytes that have passed. */
    032    private long count = 0;
    033
    034    /**
    035     * Constructs a new CountingOutputStream.
    036     *
    037     * @param out  the OutputStream to write to
    038     */
    039    public CountingOutputStream( final OutputStream out ) {
    040        super(out);
    041    }
    042
    043    //-----------------------------------------------------------------------
    044
    045    /**
    046     * Updates the count with the number of bytes that are being written.
    047     *
    048     * @param n number of bytes to be written to the stream
    049     * @since 2.0
    050     */
    051    @Override
    052    protected synchronized void beforeWrite(final int n) {
    053        count += n;
    054    }
    055
    056    //-----------------------------------------------------------------------
    057    /**
    058     * The number of bytes that have passed through this stream.
    059     * <p>
    060     * NOTE: From v1.3 this method throws an ArithmeticException if the
    061     * count is greater than can be expressed by an <code>int</code>.
    062     * See {@link #getByteCount()} for a method using a <code>long</code>.
    063     *
    064     * @return the number of bytes accumulated
    065     * @throws ArithmeticException if the byte count is too large
    066     */
    067    public int getCount() {
    068        final long result = getByteCount();
    069        if (result > Integer.MAX_VALUE) {
    070            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    071        }
    072        return (int) result;
    073    }
    074
    075    /**
    076     * Set the byte count back to 0.
    077     * <p>
    078     * NOTE: From v1.3 this method throws an ArithmeticException if the
    079     * count is greater than can be expressed by an <code>int</code>.
    080     * See {@link #resetByteCount()} for a method using a <code>long</code>.
    081     *
    082     * @return the count previous to resetting
    083     * @throws ArithmeticException if the byte count is too large
    084     */
    085    public int resetCount() {
    086        final long result = resetByteCount();
    087        if (result > Integer.MAX_VALUE) {
    088            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    089        }
    090        return (int) result;
    091    }
    092
    093    /**
    094     * The number of bytes that have passed through this stream.
    095     * <p>
    096     * NOTE: This method is an alternative for <code>getCount()</code>.
    097     * It was added because that method returns an integer which will
    098     * result in incorrect count for files over 2GB.
    099     *
    100     * @return the number of bytes accumulated
    101     * @since 1.3
    102     */
    103    public synchronized long getByteCount() {
    104        return this.count;
    105    }
    106
    107    /**
    108     * Set the byte count back to 0.
    109     * <p>
    110     * NOTE: This method is an alternative for <code>resetCount()</code>.
    111     * It was added because that method returns an integer which will
    112     * result in incorrect count for files over 2GB.
    113     *
    114     * @return the count previous to resetting
    115     * @since 1.3
    116     */
    117    public synchronized long resetByteCount() {
    118        final long tmp = this.count;
    119        this.count = 0;
    120        return tmp;
    121    }
    122
    123}