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 *
028 * @version $Id: CountingOutputStream.java 1415850 2012-11-30 20:51:39Z ggregory $
029 */
030public 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( final 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 2.0
051     */
052    @Override
053    protected synchronized void beforeWrite(final 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        final 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        final 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 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 1.3
117     */
118    public synchronized long resetByteCount() {
119        final long tmp = this.count;
120        this.count = 0;
121        return tmp;
122    }
123
124}