109 lines
2.8 KiB
Java
109 lines
2.8 KiB
Java
/*
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* Copyright (C) 2013 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
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* in compliance with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under the License
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* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing permissions and limitations under
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* the License.
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*/
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package com.google.common.hash;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.io.FilterInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import com.google.common.annotations.Beta;
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/**
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* An {@link InputStream} that maintains a hash of the data read from it.
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*
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* @author Qian Huang
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* @since 16.0
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*/
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@Beta
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public final class HashingInputStream extends FilterInputStream {
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private final Hasher hasher;
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/**
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* Creates an input stream that hashes using the given {@link HashFunction} and
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* delegates all data read from it to the underlying {@link InputStream}.
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*
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* <p>
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* The {@link InputStream} should not be read from before or after the hand-off.
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*/
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public HashingInputStream(HashFunction hashFunction, InputStream in) {
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super(checkNotNull(in));
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this.hasher = checkNotNull(hashFunction.newHasher());
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}
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/**
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* Reads the next byte of data from the underlying input stream and updates the
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* hasher with the byte read.
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*/
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@Override
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public int read() throws IOException {
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int b = in.read();
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if (b != -1) {
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hasher.putByte((byte) b);
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}
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return b;
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}
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/**
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* Reads the specified bytes of data from the underlying input stream and
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* updates the hasher with the bytes read.
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*/
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@Override
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public int read(byte[] bytes, int off, int len) throws IOException {
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int numOfBytesRead = in.read(bytes, off, len);
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if (numOfBytesRead != -1) {
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hasher.putBytes(bytes, off, numOfBytesRead);
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}
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return numOfBytesRead;
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}
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/**
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* mark() is not supported for HashingInputStream
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*
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* @return {@code false} always
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*/
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@Override
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public boolean markSupported() {
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return false;
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}
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/**
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* mark() is not supported for HashingInputStream
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*/
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@Override
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public void mark(int readlimit) {
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}
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/**
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* reset() is not supported for HashingInputStream.
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*
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* @throws IOException this operation is not supported
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*/
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@Override
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public void reset() throws IOException {
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throw new IOException("reset not supported");
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}
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/**
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* Returns the {@link HashCode} based on the data read from this stream. The
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* result is unspecified if this method is called more than once on the same
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* instance.
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*/
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public HashCode hash() {
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return hasher.hash();
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}
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}
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