org.apache.commons.compress.utils.ChecksumCalculatingInputStream Maven / Gradle / Ivy
/*
* 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.compress.utils;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.Checksum;
/**
* A stream that calculates the checksum of the data read.
* @NotThreadSafe
* @since 1.14
*/
public class ChecksumCalculatingInputStream extends InputStream {
private final InputStream in;
private final Checksum checksum;
public ChecksumCalculatingInputStream(final Checksum checksum, final InputStream in) {
if ( checksum == null ){
throw new NullPointerException("Parameter checksum must not be null");
}
if ( in == null ){
throw new NullPointerException("Parameter in must not be null");
}
this.checksum = checksum;
this.in = in;
}
/**
* Reads a single byte from the stream
* @throws IOException if the underlying stream throws or the
* stream is exhausted and the Checksum doesn't match the expected
* value
*/
@Override
public int read() throws IOException {
final int ret = in.read();
if (ret >= 0) {
checksum.update(ret);
}
return ret;
}
/**
* Reads a byte array from the stream
* @throws IOException if the underlying stream throws or the
* stream is exhausted and the Checksum doesn't match the expected
* value
*/
@Override
public int read(final byte[] b) throws IOException {
return read(b, 0, b.length);
}
/**
* Reads from the stream into a byte array.
* @throws IOException if the underlying stream throws or the
* stream is exhausted and the Checksum doesn't match the expected
* value
*/
@Override
public int read(final byte[] b, final int off, final int len) throws IOException {
final int ret = in.read(b, off, len);
if (ret >= 0) {
checksum.update(b, off, ret);
}
return ret;
}
@Override
public long skip(final long n) throws IOException {
// Can't really skip, we have to hash everything to verify the checksum
if (read() >= 0) {
return 1;
}
return 0;
}
/**
* Returns the calculated checksum.
* @return the calculated checksum.
*/
public long getValue() {
return checksum.getValue();
}
}