001package org.eclipse.aether.spi.connector.checksum;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import java.nio.ByteBuffer;
023
024/**
025 * Implementation performing checksum calculation for specific algorithm. Instances of this interface are stateful,
026 * non-thread safe, and should not be reused.
027 *
028 * @since 1.8.0
029 */
030public interface ChecksumAlgorithm
031{
032    /**
033     * Updates the checksum algorithm inner state with input.
034     */
035    void update( ByteBuffer input );
036
037    /**
038     * Returns the algorithm end result as string, never {@code null}. After invoking this method, this instance should
039     * be discarded and not reused. For new checksum calculation you have to get new instance.
040     *
041     * Values returned by this method are handled as "opaque strings", and are used for simple equality checks (matches
042     * or not matches the checksum), and are also persisted in this form (locally to file system but also uploaded as
043     * checksum files). Resolver itself never tries to "decode" or "interpret" this string in any other way.
044     */
045    String checksum();
046}