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.input;
018
019import static org.apache.commons.io.IOUtils.EOF;
020
021import java.io.IOException;
022import java.io.InputStream;
023
024/**
025 * A decorating input stream that counts the number of bytes that have passed
026 * through the stream so far.
027 * <p>
028 * A typical use case would be during debugging, to ensure that data is being
029 * read as expected.
030 *
031 */
032public class CountingInputStream extends ProxyInputStream {
033
034    /** The count of bytes that have passed. */
035    private long count;
036
037    /**
038     * Constructs a new CountingInputStream.
039     *
040     * @param in  the InputStream to delegate to
041     */
042    public CountingInputStream(final InputStream in) {
043        super(in);
044    }
045
046    //-----------------------------------------------------------------------
047
048    /**
049     * Skips the stream over the specified number of bytes, adding the skipped
050     * amount to the count.
051     *
052     * @param length  the number of bytes to skip
053     * @return the actual number of bytes skipped
054     * @throws IOException if an I/O error occurs
055     * @see java.io.InputStream#skip(long)
056     */
057    @Override
058    public synchronized long skip(final long length) throws IOException {
059        final long skip = super.skip(length);
060        this.count += skip;
061        return skip;
062    }
063
064    /**
065     * Adds the number of read bytes to the count.
066     *
067     * @param n number of bytes read, or -1 if no more bytes are available
068     * @since 2.0
069     */
070    @Override
071    protected synchronized void afterRead(final int n) {
072        if (n != EOF) {
073            this.count += n;
074        }
075    }
076
077    //-----------------------------------------------------------------------
078    /**
079     * The number of bytes that have passed through this stream.
080     * <p>
081     * NOTE: From v1.3 this method throws an ArithmeticException if the
082     * count is greater than can be expressed by an <code>int</code>.
083     * See {@link #getByteCount()} for a method using a <code>long</code>.
084     *
085     * @return the number of bytes accumulated
086     * @throws ArithmeticException if the byte count is too large
087     */
088    public int getCount() {
089        final long result = getByteCount();
090        if (result > Integer.MAX_VALUE) {
091            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
092        }
093        return (int) result;
094    }
095
096    /**
097     * Set the byte count back to 0.
098     * <p>
099     * NOTE: From v1.3 this method throws an ArithmeticException if the
100     * count is greater than can be expressed by an <code>int</code>.
101     * See {@link #resetByteCount()} for a method using a <code>long</code>.
102     *
103     * @return the count previous to resetting
104     * @throws ArithmeticException if the byte count is too large
105     */
106    public int resetCount() {
107        final long result = resetByteCount();
108        if (result > Integer.MAX_VALUE) {
109            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
110        }
111        return (int) result;
112    }
113
114    /**
115     * The number of bytes that have passed through this stream.
116     * <p>
117     * NOTE: This method is an alternative for <code>getCount()</code>
118     * and was added because that method returns an integer which will
119     * result in incorrect count for files over 2GB.
120     *
121     * @return the number of bytes accumulated
122     * @since 1.3
123     */
124    public synchronized long getByteCount() {
125        return this.count;
126    }
127
128    /**
129     * Set the byte count back to 0.
130     * <p>
131     * NOTE: This method is an alternative for <code>resetCount()</code>
132     * and was added because that method returns an integer which will
133     * result in incorrect count for files over 2GB.
134     *
135     * @return the count previous to resetting
136     * @since 1.3
137     */
138    public synchronized long resetByteCount() {
139        final long tmp = this.count;
140        this.count = 0;
141        return tmp;
142    }
143
144}