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Commons IO example source code file (CountingInputStream.java)

This example Commons IO source code file (CountingInputStream.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons IO tags/keywords

arithmeticexception, arithmeticexception, countinginputstream, countinginputstream, io, ioexception, override, override, proxyinputstream, the, the

The Commons IO CountingInputStream.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.input;

import java.io.IOException;
import java.io.InputStream;

/**
 * A decorating input stream that counts the number of bytes that have passed
 * through the stream so far.
 * <p>
 * A typical use case would be during debugging, to ensure that data is being
 * read as expected.
 *
 * @author Marcelo Liberato
 * @version $Id: CountingInputStream.java 1004079 2010-10-04 01:11:27Z niallp $
 */
public class CountingInputStream extends ProxyInputStream {

    /** The count of bytes that have passed. */
    private long count;

    /**
     * Constructs a new CountingInputStream.
     *
     * @param in  the InputStream to delegate to
     */
    public CountingInputStream(InputStream in) {
        super(in);
    }

    //-----------------------------------------------------------------------

    /**
     * Skips the stream over the specified number of bytes, adding the skipped
     * amount to the count.
     *
     * @param length  the number of bytes to skip
     * @return the actual number of bytes skipped
     * @throws IOException if an I/O error occurs
     * @see java.io.InputStream#skip(long)
     */
    @Override
    public synchronized long skip(final long length) throws IOException {
        final long skip = super.skip(length);
        this.count += skip;
        return skip;
    }

    /**
     * Adds the number of read bytes to the count.
     *
     * @param n number of bytes read, or -1 if no more bytes are available
     * @since Commons IO 2.0
     */
    @Override
    protected synchronized void afterRead(int n) {
        if (n != -1) {
            this.count += n;
        }
    }

    //-----------------------------------------------------------------------
    /**
     * The number of bytes that have passed through this stream.
     * <p>
     * NOTE: From v1.3 this method throws an ArithmeticException if the
     * count is greater than can be expressed by an <code>int.
     * See {@link #getByteCount()} for a method using a <code>long.
     *
     * @return the number of bytes accumulated
     * @throws ArithmeticException if the byte count is too large
     */
    public int getCount() {
        long result = getByteCount();
        if (result > Integer.MAX_VALUE) {
            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
        }
        return (int) result;
    }

    /** 
     * Set the byte count back to 0. 
     * <p>
     * NOTE: From v1.3 this method throws an ArithmeticException if the
     * count is greater than can be expressed by an <code>int.
     * See {@link #resetByteCount()} for a method using a <code>long.
     *
     * @return the count previous to resetting
     * @throws ArithmeticException if the byte count is too large
     */
    public int resetCount() {
        long result = resetByteCount();
        if (result > Integer.MAX_VALUE) {
            throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
        }
        return (int) result;
    }

    /**
     * The number of bytes that have passed through this stream.
     * <p>
     * NOTE: This method is an alternative for <code>getCount()
     * and was added because that method returns an integer which will
     * result in incorrect count for files over 2GB.
     *
     * @return the number of bytes accumulated
     * @since Commons IO 1.3
     */
    public synchronized long getByteCount() {
        return this.count;
    }

    /** 
     * Set the byte count back to 0. 
     * <p>
     * NOTE: This method is an alternative for <code>resetCount()
     * and was added because that method returns an integer which will
     * result in incorrect count for files over 2GB.
     *
     * @return the count previous to resetting
     * @since Commons IO 1.3
     */
    public synchronized long resetByteCount() {
        long tmp = this.count;
        this.count = 0;
        return tmp;
    }

}

Other Commons IO examples (source code examples)

Here is a short list of links related to this Commons IO CountingInputStream.java source code file:



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