Java HmacSHA256

借助bouncycastle实现HmacSHA256，即带密钥的SHA256。

在线加密工具：
http://tool.oschina.net/encrypt?type=2

private static String encrytSHA256(String content, String secret) {        try {            Security.addProvider(new BouncyCastleProvider());            SecretKey secretKey = new SecretKeySpec(secret.getBytes("UTF8"),                    "HmacSHA256");            Mac mac = Mac.getInstance(secretKey.getAlgorithm());            mac.init(secretKey);            byte[] digest = mac.doFinal(content.getBytes("UTF-8"));            return new HexBinaryAdapter().marshal(digest);        } catch (Exception e) {            throw new RuntimeCryptoException("加密异常");        }    }