java Hmac加解密

public class HmacVgUtil {

private static final String HMACMD5 = "HmacMD5";
private static final String HMACSHA1 = "HmacSHA1";
private static final String CHARSET_UTF8 = "UTF-8";
/** 密钥 **/
private static final String MAC_KEY = "abcdef";

/**
 * 计算待签名字符串的 HMAC-MD5 值
 * @param bytes
 * @param key
 * @return
 * @throws IOException 
 * @throws NoSuchAlgorithmException 
 */
public static byte[] encrypt(byte[] bytes, String key) throws Exception {
    if (isEmpty(key)) {
        throw new IOException("secret can not be empty");
    }
    
    SecretKey skey = new SecretKeySpec(key.getBytes("UTF-8"), HMACMD5);
    Mac mac = Mac.getInstance(HMACMD5);
    mac.init(skey);
    mac.update(bytes);

    return mac.doFinal();
}

/**
 * 计算待签名字符串的 HMAC-SHA1 值
 */
public static byte[] hmacSHA1Signature(String key, String baseString) throws Exception {
    if (isEmpty(key)) {
        throw new IOException("secret can not be empty");
    }
    if (isEmpty(baseString)) {
        return null;
    }
    Mac mac = Mac.getInstance("HmacSHA1");
    SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(CHARSET_UTF8), HMACSHA1);
    mac.init(keySpec);
    
    return mac.doFinal(baseString.getBytes(CHARSET_UTF8));
}

private static boolean isEmpty(String str) {
    return (str == null || str.length() == 0);
}

/**
 * 计算待签名字符串的 HMAC-MD5 值（Key是16进制字符串时使用）
 * @param bytes
 * @param key
 * @return
 * @throws Exception
 */
public static byte[] encrypt1(byte[] bytes, String key) throws Exception {
    if (isEmpty(key)) {
        throw new IOException("secret can not be empty");
    }
     int m = 0, n = 0;
    int l = key.length() / 2;
    byte[] ret = new byte[l];
    for (int i = 0; i < l; i++) {
        m = i * 2 + 1;
        n = m + 1;
        ret[i] = Byte.decode("0x" + key.substring(i * 2, m) + key.substring(m, n));
    }
    SecretKey skey = new SecretKeySpec(ret, HMACMD5);
    Mac mac = Mac.getInstance(HMACMD5);
    mac.init(skey);
    mac.update(bytes);

    return mac.doFinal();
}

}