MD5加密

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Encodes a string using MD5 hashing
 * 
 * @author Rafael Steil
 * @version $Id: MD5.java,v 1.7 2006/08/23 02:13:44 rafaelsteil Exp $
 */
public class MD5 {
	/**
	 * Encodes a string
	 * 
	 * @param str
	 *            String to encode
	 * @return Encoded String
	 * @throws NoSuchAlgorithmException
	 */
	public static String crypt(String str) {
		if (str == null || str.length() == 0) {
			throw new IllegalArgumentException(
					"String to encript cannot be null or zero length");
		}

		StringBuilder hexString = new StringBuilder();

		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(str.getBytes());
			byte[] hash = md.digest();

			for (int i = 0; i < hash.length; i++) {
				if ((0xff & hash[i]) < 0x10) {
					hexString.append("0"
							+ Integer.toHexString((0xFF & hash[i])));
				} else {
					hexString.append(Integer.toHexString(0xFF & hash[i]));
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}

		return hexString.toString();
	}
}