Java兼容的cksum功能

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class Cksum {
    public static void main(String[] args) throws IOException {
        File file = new File("path/to/file");
        long cksum = calculateCksum(file);
        System.out.println("Cksum: " + cksum);
    }

    public static long calculateCksum(File file) throws IOException {
        try (FileInputStream fis = new FileInputStream(file);
             FileChannel fileChannel = fis.getChannel()) {
            long size = fileChannel.size();
            long cksum = 0;
            for (long pos = 0; pos< size; pos += Integer.MAX_VALUE) {
                long count = Math.min(size - pos, Integer.MAX_VALUE);
                ByteBuffer buffer = ByteBuffer.allocate((int) count);
                fileChannel.read(buffer, pos);
                buffer.flip();
                while (buffer.hasRemaining()) {
                    cksum += buffer.get() & 0xff;
                }
            }
            return cksum;
        }
    }
}