| /* |
| * Copyright (C) 2013 The Guava Authors |
| * |
| * Licensed 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 com.google.common.hash; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import com.google.common.annotations.Beta; |
| import com.google.errorprone.annotations.CanIgnoreReturnValue; |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * An {@link InputStream} that maintains a hash of the data read from it. |
| * |
| * @author Qian Huang |
| * @since 16.0 |
| */ |
| @Beta |
| public final class HashingInputStream extends FilterInputStream { |
| private final Hasher hasher; |
| |
| /** |
| * Creates an input stream that hashes using the given {@link HashFunction} and delegates all data |
| * read from it to the underlying {@link InputStream}. |
| * |
| * <p>The {@link InputStream} should not be read from before or after the hand-off. |
| */ |
| public HashingInputStream(HashFunction hashFunction, InputStream in) { |
| super(checkNotNull(in)); |
| this.hasher = checkNotNull(hashFunction.newHasher()); |
| } |
| |
| /** |
| * Reads the next byte of data from the underlying input stream and updates the hasher with the |
| * byte read. |
| */ |
| @Override |
| @CanIgnoreReturnValue |
| public int read() throws IOException { |
| int b = in.read(); |
| if (b != -1) { |
| hasher.putByte((byte) b); |
| } |
| return b; |
| } |
| |
| /** |
| * Reads the specified bytes of data from the underlying input stream and updates the hasher with |
| * the bytes read. |
| */ |
| @Override |
| @CanIgnoreReturnValue |
| public int read(byte[] bytes, int off, int len) throws IOException { |
| int numOfBytesRead = in.read(bytes, off, len); |
| if (numOfBytesRead != -1) { |
| hasher.putBytes(bytes, off, numOfBytesRead); |
| } |
| return numOfBytesRead; |
| } |
| |
| /** |
| * mark() is not supported for HashingInputStream |
| * |
| * @return {@code false} always |
| */ |
| @Override |
| public boolean markSupported() { |
| return false; |
| } |
| |
| /** mark() is not supported for HashingInputStream */ |
| @Override |
| public void mark(int readlimit) {} |
| |
| /** |
| * reset() is not supported for HashingInputStream. |
| * |
| * @throws IOException this operation is not supported |
| */ |
| @Override |
| public void reset() throws IOException { |
| throw new IOException("reset not supported"); |
| } |
| |
| /** |
| * Returns the {@link HashCode} based on the data read from this stream. The result is unspecified |
| * if this method is called more than once on the same instance. |
| */ |
| public HashCode hash() { |
| return hasher.hash(); |
| } |
| } |