用的是微信给的demo解密，帮忙看下哪里出了问题

public static String getSHA1(String token, String timestamp, String nonce, String encrypt) throws AesException
{
    try {
        String[] array = new String[] { token, timestamp, nonce, encrypt };
        StringBuffer sb = new StringBuffer();
        // 字符串排序
        Arrays.sort(array);
        for (int i = 0; i < 4; i++) {
            sb.append(array[i]);
        }
        String str = sb.toString();
        // SHA1签名生成
        MessageDigest md = MessageDigest.getInstance("SHA-1");
        md.update(str.getBytes());
        byte[] digest = md.digest();

        StringBuffer hexstr = new StringBuffer();
        String shaHex = "";
        for (int i = 0; i < digest.length; i++) {
            shaHex = Integer.toHexString(digest[i] & 0xFF);
            if (shaHex.length() < 2) {
                hexstr.append(0);
            }
            hexstr.append(shaHex);
        }
        return hexstr.toString();
    } catch (Exception e) {
        e.printStackTrace();
        throw new AesException(AesException.ComputeSignatureError);
    }
}