thinkPHP5.0开发微信H5页面分享接口signature验证失败，signature与微信 JS 接口签名校验工具返回结果不一致

    $access_token = new WeChat();
        $url = '' ;
        $ticket = $access_token->getJsapiTicket();
        $ticket = json_decode($ticket)->ticket;
        $noncestr = $this->createNonceStr();
        $timestamp = time();
        $string = 'jsapi_ticket=' . $ticket . '&noncestr=' . $noncestr . '&timestamp=' . $timestamp . '&url=' . $url;
        $signature = sha1($string);

    $access_token = new WeChat();
        $url = '' ;
        $ticket = $access_token->getJsapiTicket();
        $ticket = json_decode($ticket)->ticket;
        $noncestr = $this->createNonceStr();
        $timestamp = time();
        $string = 'jsapi_ticket=' . $ticket . '&noncestr=' . $noncestr . '&timestamp=' . $timestamp . '&url=' . $url;
        $signature1 = sha1(htmlspecialchars_decode($string));