/*
 *  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
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package org.apache.commons.compress.utils;

import java.io.IOException;
import java.io.InputStream;
import java.util.Objects;
import java.util.zip.Checksum;

A stream that calculates the checksum of the data read.
@NotThreadSafe
Since:1.14
/** * 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 inputStream) { Objects.requireNonNull(checksum, "checksum"); Objects.requireNonNull(inputStream, "in"); this.checksum = checksum; this.in = inputStream; }
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
/** * 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
/** * 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
/** * 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 { if (len == 0) { return 0; } 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.
Returns:the calculated checksum.
/** * Returns the calculated checksum. * @return the calculated checksum. */
public long getValue() { return checksum.getValue(); } }