MessageDigestConverter.java

package co.malm.demos.security.sha1;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Utility class that uses {@link MessageDigest} for obtaining a hashed text
 * using algorithms such as MD5 and SHA-1
 * 
 * @author marlonlom
 */
public class MessageDigestGenerator {

	/**
	 * Generates a string with selected digest algorithm
	 * 
	 * @param input
	 *            text string to convert
	 * @param algorithm
	 *            defined algorithm for use
	 * @return a generated hex string
	 * @throws NoSuchAlgorithmException
	 *             if algorithm doesn't exists
	 */
	private static String digest(String input, final String algorithm)
			throws NoSuchAlgorithmException {
		MessageDigest md = MessageDigest.getInstance(algorithm);
		byte[] digested = md.digest(input.getBytes());
		return new BigInteger(1, digested).toString(16);
	}

	/**
	 * Calculates the MD5 digest and returns the value as a hex string.
	 * 
	 * @param input
	 * @return
	 * @throws Exception
	 */
	public static String md5(String input) throws Exception {
		final String MD5 = "MD5";
		return digest(input, MD5);
	}

	/**
	 * Calculates the SHA-1 digest and returns the value as a hex string.
	 * 
	 * @param input
	 * @return
	 * @throws Exception
	 */
	public static String sha1(String input) throws Exception {
		final String SHA1 = "SHA-1";
		return digest(input, SHA1);
	}

	/**
	 * Calculates the SHA-256 digest and returns the value as a hex string.
	 * 
	 * @param input
	 * @return
	 * @throws Exception
	 */
	public static String sha256(String input) throws Exception {
		final String SHA256 = "SHA-256";
		return digest(input, SHA256);
	}

	/**
	 * Calculates the SHA-512 digest and returns the value as a hex string.
	 * 
	 * @param input
	 * @return
	 * @throws Exception
	 */
	public static String sha512(String input) throws Exception {
		final String SHA512 = "SHA-512";
		return digest(input, SHA512);
	}

}

How to use:
MessageDigestGenerator.sha256("wow, it works");
It prints > e609711a74800dfcae06f3adc3b7065439fd81892b5cf49fd2702835710bc19f