public class Encryption {

    /**
     * @param args
     */
    public static void main(String[] args) {
        System.out.println(Encryption.getMD5Str("1111"));
    }

    public static String getMD5Str(String str) {
        MessageDigest messageDigest = null;
        
        try {
            messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.reset();
            messageDigest.update(str.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
            System.out.println("NoSuchAlgorithmException caught!");
            System.exit(-1);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        
        byte [] byteArray = messageDigest.digest();
        StringBuffer md5StringBuffer = new StringBuffer();
        
        for(int i = 0; i < byteArray.length; ++ i) {
            if(Integer.toHexString(0xFF & byteArray[i]).length() == 1) {
                md5StringBuffer.append("0");
                md5StringBuffer.append(Integer.toHexString(0xFF & byteArray[i]));
            } else {
                md5StringBuffer.append(Integer.toHexString(0xFF & byteArray[i]));
            }
        }
        
        return md5StringBuffer.toString();
    }
}