    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     */
    017    package org.apache.commons.io.output;
    018
    019    import 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     * @version $Id: CountingOutputStream.java 1004079 2010-10-04 01:11:27Z niallp $
    029     */
    030    public class CountingOutputStream extends ProxyOutputStream {
    031
    032        /** The count of bytes that have passed. */
    033        private long count = 0;
    034
    035        /**
    036         * Constructs a new CountingOutputStream.
    037         *
    038         * @param out  the OutputStream to write to
    039         */
    040        public CountingOutputStream( OutputStream out ) {
    041            super(out);
    042        }
    043
    044        //-----------------------------------------------------------------------
    045
    046        /**
    047         * Updates the count with the number of bytes that are being written.
    048         *
    049         * @param n number of bytes to be written to the stream
    050         * @since Commons IO 2.0
    051         */
    052        @Override
    053        protected synchronized void beforeWrite(int n) {
    054            count += n;
    055        }
    056
    057        //-----------------------------------------------------------------------
    058        /**
    059         * The number of bytes that have passed through this stream.
    060         * <p>
    061         * NOTE: From v1.3 this method throws an ArithmeticException if the
    062         * count is greater than can be expressed by an <code>int</code>.
    063         * See {@link #getByteCount()} for a method using a <code>long</code>.
    064         *
    065         * @return the number of bytes accumulated
    066         * @throws ArithmeticException if the byte count is too large
    067         */
    068        public int getCount() {
    069            long result = getByteCount();
    070            if (result > Integer.MAX_VALUE) {
    071                throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    072            }
    073            return (int) result;
    074        }
    075
    076        /**
    077         * Set the byte count back to 0.
    078         * <p>
    079         * NOTE: From v1.3 this method throws an ArithmeticException if the
    080         * count is greater than can be expressed by an <code>int</code>.
    081         * See {@link #resetByteCount()} for a method using a <code>long</code>.
    082         *
    083         * @return the count previous to resetting
    084         * @throws ArithmeticException if the byte count is too large
    085         */
    086        public int resetCount() {
    087            long result = resetByteCount();
    088            if (result > Integer.MAX_VALUE) {
    089                throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    090            }
    091            return (int) result;
    092        }
    093
    094        /**
    095         * The number of bytes that have passed through this stream.
    096         * <p>
    097         * NOTE: This method is an alternative for <code>getCount()</code>.
    098         * It was added because that method returns an integer which will
    099         * result in incorrect count for files over 2GB.
    100         *
    101         * @return the number of bytes accumulated
    102         * @since Commons IO 1.3
    103         */
    104        public synchronized long getByteCount() {
    105            return this.count;
    106        }
    107
    108        /**
    109         * Set the byte count back to 0.
    110         * <p>
    111         * NOTE: This method is an alternative for <code>resetCount()</code>.
    112         * It was added because that method returns an integer which will
    113         * result in incorrect count for files over 2GB.
    114         *
    115         * @return the count previous to resetting
    116         * @since Commons IO 1.3
    117         */
    118        public synchronized long resetByteCount() {
    119            long tmp = this.count;
    120            this.count = 0;
    121            return tmp;
    122        }
    123
    124    }