net.nicoulaj.maven.plugins.checksum.digest.CRC32FileDigester Maven / Gradle / Ivy

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/*
 * checksum-maven-plugin - http://checksum-maven-plugin.nicoulaj.net
 * Copyright © 2010-2018 checksum-maven-plugin contributors
 *
 * 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 net.nicoulaj.maven.plugins.checksum.digest;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;

/**
 * Implementation of {@link FileDigester} for the CRC32 algorithm.
 *
 * @author Julien Nicoulaud
 * @see FileDigester
 * @since 1.0
 */
public class CRC32FileDigester
    extends AbstractFileDigester
{
    /**
     * The identifier of the algorithm supported by this implementation.
     */
    public static final String ALGORITHM = "CRC32";

    /**
     * Build a new instance of {@link CRC32FileDigester}.
     */
    public CRC32FileDigester()
    {
        super( ALGORITHM );
    }

    /**
     * {@inheritDoc}
     */
    public String calculate( File file )
        throws DigesterException
    {
        CheckedInputStream cis;
        try
        {
            cis = new CheckedInputStream( new FileInputStream( file ), new CRC32() );
        }
        catch ( FileNotFoundException e )
        {
            throw new DigesterException( "Unable to read " + file.getPath() + ": " + e.getMessage() );
        }

        byte[] buf = new byte[STREAMING_BUFFER_SIZE];
        try
        {
            while ( cis.read( buf ) >= 0 )
            {
                continue;
            }
        }
        catch ( IOException e )
        {
            throw new DigesterException(
                "Unable to calculate the " + getAlgorithm() + " hashcode for " + file.getPath() + ": "
                    + e.getMessage() );
        }

        return Long.toString( cis.getChecksum().getValue() );
    }
}