Java MD5加密

public class MD5Util {
    public static String getMD5(String str) {
        MessageDigest md = null;
        try {
            md = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            return "";
        }
        byte[] input = str.getBytes();
        byte[] buff = md.digest(input);
        return bytesToHex(buff);
    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder md5str = new StringBuilder();
        int digital;
        for (byte aByte : bytes) {
            digital = aByte;

            if (digital < 0) {
                digital += 256;
            }
            if (digital < 16) {
                md5str.append("0");
            }
            md5str.append(Integer.toHexString(digital));
        }
        return md5str.toString().toUpperCase();
    }
}