001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.internal.impl.checksum;
020
021import java.nio.ByteBuffer;
022import java.security.MessageDigest;
023import java.security.NoSuchAlgorithmException;
024
025import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithm;
026import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactory;
027import org.eclipse.aether.spi.connector.checksum.ChecksumAlgorithmFactorySupport;
028import org.eclipse.aether.util.StringDigestUtil;
029
030/**
031 * Support class to implement {@link ChecksumAlgorithmFactory} based on Java {@link MessageDigest}.
032 *
033 * @since 1.8.0
034 */
035public abstract class MessageDigestChecksumAlgorithmFactorySupport extends ChecksumAlgorithmFactorySupport {
036    public MessageDigestChecksumAlgorithmFactorySupport(String name, String extension) {
037        super(name, extension);
038    }
039
040    @Override
041    public ChecksumAlgorithm getAlgorithm() {
042        try {
043            MessageDigest messageDigest = MessageDigest.getInstance(getName());
044            return new ChecksumAlgorithm() {
045                @Override
046                public void update(final ByteBuffer input) {
047                    messageDigest.update(input);
048                }
049
050                @Override
051                public String checksum() {
052                    return StringDigestUtil.toHexString(messageDigest.digest());
053                }
054            };
055        } catch (NoSuchAlgorithmException e) {
056            throw new IllegalStateException(
057                    "MessageDigest algorithm " + getName() + " not supported, but is required by resolver.", e);
058        }
059    }
060}