    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 * </p>
    028 *
    029 */
    030public class CountingOutputStream extends ProxyOutputStream {
    031
    032    /** The count of bytes that have passed. */
    033    private long count;
    034
    035    /**
    036     * Constructs a new CountingOutputStream.
    037     *
    038     * @param out  the OutputStream to write to
    039     */
    040    public CountingOutputStream( final OutputStream out ) {
    041        super(out);
    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     * The number of bytes that have passed through this stream.
    058     * <p>
    059     * NOTE: From v1.3 this method throws an ArithmeticException if the
    060     * count is greater than can be expressed by an {@code int}.
    061     * See {@link #getByteCount()} for a method using a {@code long}.
    062     *
    063     * @return the number of bytes accumulated
    064     * @throws ArithmeticException if the byte count is too large
    065     */
    066    public int getCount() {
    067        final long result = getByteCount();
    068        if (result > Integer.MAX_VALUE) {
    069            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    070        }
    071        return (int) result;
    072    }
    073
    074    /**
    075     * Set the byte count back to 0.
    076     * <p>
    077     * NOTE: From v1.3 this method throws an ArithmeticException if the
    078     * count is greater than can be expressed by an {@code int}.
    079     * See {@link #resetByteCount()} for a method using a {@code long}.
    080     *
    081     * @return the count previous to resetting
    082     * @throws ArithmeticException if the byte count is too large
    083     */
    084    public int resetCount() {
    085        final long result = resetByteCount();
    086        if (result > Integer.MAX_VALUE) {
    087            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    088        }
    089        return (int) result;
    090    }
    091
    092    /**
    093     * The number of bytes that have passed through this stream.
    094     * <p>
    095     * NOTE: This method is an alternative for {@code getCount()}.
    096     * It was added because that method returns an integer which will
    097     * result in incorrect count for files over 2GB.
    098     *
    099     * @return the number of bytes accumulated
    100     * @since 1.3
    101     */
    102    public synchronized long getByteCount() {
    103        return this.count;
    104    }
    105
    106    /**
    107     * Set the byte count back to 0.
    108     * <p>
    109     * NOTE: This method is an alternative for {@code resetCount()}.
    110     * It was added because that method returns an integer which will
    111     * result in incorrect count for files over 2GB.
    112     *
    113     * @return the count previous to resetting
    114     * @since 1.3
    115     */
    116    public synchronized long resetByteCount() {
    117        final long tmp = this.count;
    118        this.count = 0;
    119        return tmp;
    120    }
    121
    122}