How can I hash with the MD5 for file

Question

I am a new learner in Java.
Is there any useful code example or materials for me to learn how can i hash with MD5 for file.

Answer 1

import java.security.*;
import sun.security.provider.Sun;
import java.io.*;
import sun.misc.*;
public class DigestOfFile
    public DigestOfFile(String mode) throws Exception
        assert(mode != null);
        digestAgent = MessageDigest.getInstance(mode, "SUN");
    synchronized public byte[] digestAsByteArray(File file) throws Exception
        assert(file != null);
        digestAgent.reset();
        InputStream is = new BufferedInputStream(new FileInputStream(file));
        for (int bytesRead = 0; (bytesRead = is.read(buffer)) >= 0;)
            digestAgent.update(buffer, 0, bytesRead);
        is.close();
        byte[] digest = digestAgent.digest();
        return digest;
    synchronized public String digestAsBase64(File file) throws Exception
        byte[] digest = digestAsByteArray(file);
        String digestAsBase64 = base64Encoder.encode(digest);
        return digestAsBase64;
    synchronized public String digestAsHex(File file) throws Exception
        byte[] digest = digestAsByteArray(file);
        String digestAsHex = encodeBytesAsHex(digest);
        return digestAsHex;
    private static String encodeBytesAsHex(byte[] bites)
        char[] hexChars = new char[bites.length*2];
        for (int charIndex = 0, startIndex = 0; charIndex < hexChars.length;)
            int bite = bites[startIndex++] & 0xff;
            hexChars[charIndex++] = HEX_CHARS[bite >> 4];
            hexChars[charIndex++] = HEX_CHARS[bite & 0xf];
        return new String(hexChars);
    private static final char[] HEX_CHARS =
    {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
    private MessageDigest digestAgent;
    private BASE64Encoder base64Encoder = new BASE64Encoder();
    private byte[] buffer = new byte[4096];
    public static void main(String[] args)
        try
            java.security.Security.addProvider(new Sun());
            DigestOfFile shaDigestAgent = new DigestOfFile("SHA");
            DigestOfFile md5DigestAgent = new DigestOfFile("MD5");
            for (int argIndex = 0; argIndex < args.length; argIndex++)
                    String base64Digest = shaDigestAgent.digestAsBase64(new File(args[argIndex]));
                    System.out.println("Base64 SHA of " + args[argIndex] + " = [" + base64Digest + "]");
                    String hexDigest = shaDigestAgent.digestAsHex(new File(args[argIndex]));
                    System.out.println("Hex    SHA of " + args[argIndex] + " = [" + hexDigest + "]");
                    String base64Digest = md5DigestAgent.digestAsBase64(new File(args[argIndex]));
                    System.out.println("Base64 MD5 of " + args[argIndex] + " = [" + base64Digest + "]");
                    String hexDigest = md5DigestAgent.digestAsHex(new File(args[argIndex]));
                    System.out.println("Hex    MD5 of " + args[argIndex] + " = [" + hexDigest + "]");
        catch (Exception e)
            e.printStackTrace(System.out);
}