checkSum

StatelessRealm.java

package util;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.zip.CRC32;
import org.flywaydb.core.api.FlywayException;
import org.flywaydb.core.internal.util.scanner.Resource;
import org.flywaydb.core.internal.util.scanner.filesystem.FileSystemResource;

/**
 * @author zhangweixiao - 19-2-22
 */
public class CheckSum {

    /**
     * Calculates the checksum of this string.
     *
     * @param filePath 脚本文件的绝对路径
     * @return The crc-32 checksum of the bytes.
     * @throws Exception
     */
    /* private -> for testing */
   public static int calculateChecksum(String filePath) throws Exception {

       Resource  resource = new FileSystemResource(filePath);

        final CRC32 crc32 = new CRC32();

        BufferedReader bufferedReader = new BufferedReader(new FileReader(filePath));
        try {
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                crc32.update(line.getBytes("UTF-8"));
            }
        } catch (IOException e) {
            String message = "Unable to calculate checksum";
            if (resource != null) {
                message += " for " + resource.getLocation() + " (" + resource.getLocationOnDisk() + ")";
            }
            throw new FlywayException(message, e);
        }

        return (int) crc32.getValue();
    }

    public static void main(String[] args) throws Exception {
        System.out.println(calculateChecksum("/home/zhenyu/work/rmb/rmb-uc2b/src/main/resources/db/migration/V2_23_20190411170201__dml.sql"));
    }

}