org.apache.commons.io.input.CountingInputStream Maven / Gradle / Ivy
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/*
* 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 static org.apache.commons.io.IOUtils.EOF;
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.
*
* A typical use case would be during debugging, to ensure that data is being
* read as expected.
*
*/
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(final 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 2.0
*/
@Override
protected synchronized void afterRead(final int n) {
if (n != EOF) {
this.count += n;
}
}
//-----------------------------------------------------------------------
/**
* The number of bytes that have passed through this stream.
*
* NOTE: From v1.3 this method throws an ArithmeticException if the
* count is greater than can be expressed by an int.
* See {@link #getByteCount()} for a method using a long.
*
* @return the number of bytes accumulated
* @throws ArithmeticException if the byte count is too large
*/
public int getCount() {
final 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.
*
* NOTE: From v1.3 this method throws an ArithmeticException if the
* count is greater than can be expressed by an int.
* See {@link #resetByteCount()} for a method using a long.
*
* @return the count previous to resetting
* @throws ArithmeticException if the byte count is too large
*/
public int resetCount() {
final 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.
*
* NOTE: This method is an alternative for 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 1.3
*/
public synchronized long getByteCount() {
return this.count;
}
/**
* Set the byte count back to 0.
*
* NOTE: This method is an alternative for 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 1.3
*/
public synchronized long resetByteCount() {
final long tmp = this.count;
this.count = 0;
return tmp;
}
}