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 */
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    /**
045     * Updates the count with the number of bytes that are being written.
046     *
047     * @param n number of bytes to be written to the stream
048     * @since 2.0
049     */
050    @Override
051    protected synchronized void beforeWrite(final int n) {
052        count += n;
053    }
054
055    /**
056     * The number of bytes that have passed through this stream.
057     * <p>
058     * NOTE: This method is an alternative for {@code getCount()}.
059     * It was added because that method returns an integer which will
060     * result in incorrect count for files over 2GB.
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     * 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     *
076     * @return the number of bytes accumulated
077     * @throws ArithmeticException if the byte count is too large
078     */
079    public int getCount() {
080        final long result = getByteCount();
081        if (result > Integer.MAX_VALUE) {
082            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
083        }
084        return (int) result;
085    }
086
087    /**
088     * Set the byte count back to 0.
089     * <p>
090     * NOTE: This method is an alternative for {@code resetCount()}.
091     * It was added because that method returns an integer which will
092     * result in incorrect count for files over 2GB.
093     *
094     * @return the count previous to resetting
095     * @since 1.3
096     */
097    public synchronized long resetByteCount() {
098        final long tmp = this.count;
099        this.count = 0;
100        return tmp;
101    }
102
103    /**
104     * Set the byte count back to 0.
105     * <p>
106     * NOTE: From v1.3 this method throws an ArithmeticException if the
107     * count is greater than can be expressed by an {@code int}.
108     * See {@link #resetByteCount()} for a method using a {@code long}.
109     *
110     * @return the count previous to resetting
111     * @throws ArithmeticException if the byte count is too large
112     */
113    public int resetCount() {
114        final long result = resetByteCount();
115        if (result > Integer.MAX_VALUE) {
116            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
117        }
118        return (int) result;
119    }
120
121}