MD5 with Java

MD5.java

import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5 {

    public static void main(String[] args)
    throws IOException, NoSuchAlgorithmException {

        InputStream in = new FileInputStream(args[0]);

        try {
            System.out.println(md5(in));
        } finally {
            in.close();
        }

        System.out.println(md5(args[0].getBytes()));
    }


    public static String md5(byte[] b)
    throws IOException, NoSuchAlgorithmException {
        return md5(new ByteArrayInputStream(b));
    }


    public static String md5(InputStream in)
    throws IOException, NoSuchAlgorithmException {

        MessageDigest md5 = MessageDigest.getInstance("MD5");

        byte[] buf = new byte[1024];

        int i = 0;
        while ((i = in.read(buf)) > -1) {
            md5.update(buf, 0, i);
        }
        return toHexString(md5.digest());
    }


    public static String md5(ReadableByteChannel r)
    throws IOException, NoSuchAlgorithmException {

        MessageDigest md5 = MessageDigest.getInstance("MD5");

        ByteBuffer buf = ByteBuffer.allocate(1024);
        while (r.read(buf) > -1) {
            buf.flip();
            md5.update(buf);
            buf.clear();
        }
        return toHexString(md5.digest());
    }


    private static String toHexString(byte[] b) {
        StringBuilder s = new StringBuilder();
        for (int i = 0; i < b.length; i++) {
            int x = b[i] & 0xff;
              if (x < 0x10) {
                  s.append("0");
              }
               s.append(Integer.toHexString(x));
        }
        return s.toString();
    }
}