公众号消息推送

$token = 'wxtoken';//1HM81QCkehYncv0cph337Dp3PYHA05lDRu43P2vWDxM
        $signature = $_GET["signature"];
        $timestamp = $_GET["timestamp"];
        $nonce = $_GET["nonce"];
        $echostr = $_GET['echostr'];
        $array = array($token, $timestamp, $nonce);
        sort($array);
        $arrayStr = implode($array);
        $arrayStr = sha1($arrayStr);
        if ($signature == $arrayStr) {
            $file= fopen('weixin.txt', 'w');
            fclose($file);
            echo $echostr;
        } else {
            return false;
        }
        exit();