MD5加密工具类

MD5加密工具类

public class MD5 {

    /**
     * 
     * @param str
     * @param bit
     * @return
     */
    private static String crypt(String str, int bit) {
        if (str == null || str.length() == 0) {
            throw new IllegalArgumentException(
                    "String to encript cannot be null or zero length");
        }

        StringBuffer hexString = new StringBuffer();

        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 (NoSuchAlgorithmException e) {
        }

        if (1 == bit) {
            return hexString.toString();
        } else {
            return StringUtils.substring(hexString.toString(), 8, 24);
        }
    }

    /**
     * MD5摘要.
     * 
     * @param text
     *            摘要文本
     * @param bit
     *            位数（1:256;2:128）
     * @return
     */
    public static String encode(String text, int bit) {
        return crypt(text, bit);
    }

}