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     * </p>
062     *
063     * @return the number of bytes accumulated
064     * @since 1.3
065     */
066    public synchronized long getByteCount() {
067        return this.count;
068    }
069
070    /**
071     * Gets the number of bytes that have passed through this stream.
072     * <p>
073     * NOTE: From v1.3 this method throws an ArithmeticException if the
074     * count is greater than can be expressed by an {@code int}.
075     * See {@link #getByteCount()} for a method using a {@code long}.
076     * </p>
077     *
078     * @return the number of bytes accumulated
079     * @throws ArithmeticException if the byte count is too large
080     */
081    public int getCount() {
082        final long result = getByteCount();
083        if (result > Integer.MAX_VALUE) {
084            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
085        }
086        return (int) result;
087    }
088
089    /**
090     * Sets the byte count back to 0.
091     * <p>
092     * NOTE: This method is an alternative for {@code resetCount()}.
093     * It was added because that method returns an integer which will
094     * result in incorrect count for files over 2GB.
095     * </p>
096     *
097     * @return the count previous to resetting
098     * @since 1.3
099     */
100    public synchronized long resetByteCount() {
101        final long tmp = this.count;
102        this.count = 0;
103        return tmp;
104    }
105
106    /**
107     * Sets the byte count back to 0.
108     * <p>
109     * NOTE: From v1.3 this method throws an ArithmeticException if the
110     * count is greater than can be expressed by an {@code int}.
111     * See {@link #resetByteCount()} for a method using a {@code long}.
112     * </p>
113     *
114     * @return the count previous to resetting
115     * @throws ArithmeticException if the byte count is too large
116     */
117    public int resetCount() {
118        final long result = resetByteCount();
119        if (result > Integer.MAX_VALUE) {
120            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
121        }
122        return (int) result;
123    }
124
125}