CRCChecksum.java

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/* *********************************************************************** *
 * project: org.matsim.*
 * CRCChecksum.java
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 * copyright       : (C) 2007 by the members listed in the COPYING,        *
 *                   LICENSE and WARRANTY file.                            *
 * email           : info at matsim dot org                                *
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *   See also COPYING, LICENSE and WARRANTY file                           *
 *                                                                         *
 * *********************************************************************** */

package org.matsim.core.utils.misc;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.GZIPInputStream;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class CRCChecksum {
    private static final Logger log = LogManager.getLogger( CRCChecksum.class );

    private static long getCRCFromStream(final InputStream in) {
        long check = 0;
        if (in == null) return 0;
        CRC32 crc = new CRC32();
        try (CheckedInputStream cis = new CheckedInputStream(in, crc)) {
            byte[] buffer = new byte[4096];
            while (cis.read(buffer) != -1) {
                /* Read until the end of the stream is reached. */
            }
            check = crc.getValue();
            cis.close();
        }
        catch (IOException e) {
            throw new RuntimeException(e);
        }
        return check;
    }

    public static long getCRCFromFile(final String filename) {
        log.info("filename=" + filename ) ;
        if (new File(filename).exists()) {
            log.info( "file exists");
            if (filename.endsWith(".gz")) {
                log.info( "file ends in gz");
                try ( InputStream in = new GZIPInputStream(new BufferedInputStream(new FileInputStream(filename))) ) {
                    long result = getCRCFromStream(in);
                    in.close();
                    return result ;
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } else { // not with gz
                log.info( "file does not end in gz");
                try ( InputStream in = new BufferedInputStream(new FileInputStream(filename)) ) {
                    long result = getCRCFromStream(in);
                    in.close();
                    return result ;
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
        } else { // does not exist
            log.info( "file does not exist; search via class loader");
            // (the logic is: if the file cannot be found directly on the file system, this is some method to search
            // in generic locations (which ones?).  kai, feb'14)
            if (filename.endsWith(".gz")) {
                log.info( "file ends in gz");
                try ( InputStream stream = CRCChecksum.class.getClassLoader().getResourceAsStream(filename) ;
                    InputStream in = new GZIPInputStream(new BufferedInputStream(stream))) {
                    long result = getCRCFromStream(in);
                    in.close();
                    return result ;
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } else { // not work gz
                log.info( "file does not end in gz");
                try ( InputStream stream = CRCChecksum.class.getClassLoader().getResourceAsStream(filename) ;
                    InputStream in = new BufferedInputStream(stream)) {
                    long result = getCRCFromStream(in);
                    in.close();
                    return result ;
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }
}