    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.
    024 * <p>
    025 * A typical use case would be during debugging, to ensure that data is being
    026 * written as expected.
    027 * </p>
    028 */
    029public class CountingOutputStream extends ProxyOutputStream {
    030
    031    /** The count of bytes that have passed. */
    032    private long count;
    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     * Updates the count with the number of bytes that are being written.
    045     *
    046     * @param n number of bytes to be written to the stream
    047     * @since 2.0
    048     */
    049    @Override
    050    protected synchronized void beforeWrite(final int n) {
    051        count += n;
    052    }
    053
    054    /**
    055     * The number of bytes that have passed through this stream.
    056     * <p>
    057     * NOTE: This method is an alternative for {@code getCount()}.
    058     * It was added because that method returns an integer which will
    059     * result in incorrect count for files over 2GB.
    060     * </p>
    061     *
    062     * @return the number of bytes accumulated
    063     * @since 1.3
    064     */
    065    public synchronized long getByteCount() {
    066        return this.count;
    067    }
    068
    069    /**
    070     * Gets the number of bytes that have passed through this stream.
    071     * <p>
    072     * NOTE: From v1.3 this method throws an ArithmeticException if the
    073     * count is greater than can be expressed by an {@code int}.
    074     * See {@link #getByteCount()} for a method using a {@code long}.
    075     * </p>
    076     *
    077     * @return the number of bytes accumulated
    078     * @throws ArithmeticException if the byte count is too large
    079     */
    080    public int getCount() {
    081        final long result = getByteCount();
    082        if (result > Integer.MAX_VALUE) {
    083            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    084        }
    085        return (int) result;
    086    }
    087
    088    /**
    089     * Sets the byte count back to 0.
    090     * <p>
    091     * NOTE: This method is an alternative for {@code resetCount()}.
    092     * It was added because that method returns an integer which will
    093     * result in incorrect count for files over 2GB.
    094     * </p>
    095     *
    096     * @return the count previous to resetting
    097     * @since 1.3
    098     */
    099    public synchronized long resetByteCount() {
    100        final long tmp = this.count;
    101        this.count = 0;
    102        return tmp;
    103    }
    104
    105    /**
    106     * Sets the byte count back to 0.
    107     * <p>
    108     * NOTE: From v1.3 this method throws an ArithmeticException if the
    109     * count is greater than can be expressed by an {@code int}.
    110     * See {@link #resetByteCount()} for a method using a {@code long}.
    111     * </p>
    112     *
    113     * @return the count previous to resetting
    114     * @throws ArithmeticException if the byte count is too large
    115     */
    116    public int resetCount() {
    117        final long result = resetByteCount();
    118        if (result > Integer.MAX_VALUE) {
    119            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
    120        }
    121        return (int) result;
    122    }
    123
    124}