php微信开发 接口配置信息 如何代码实现，代码实现，入口文件 token 配置失败

<?php
/**
* Created by PhpStorm.
* User: liaosp
* Date: 2017/8/23
* Time: 10:36
*/

$timestamp = $_GET['timestamp'];
$nonce = $_GET['nonce'];
$token = 'weixin';  //在网页中配置的token
$signature = $_GET['signature'];
$array = array($timestamp,$nonce,$token);
$tmpstr= implode('',$array);
$tmpstr = sha1($tmpstr);
if ($tmpstr == $signature){
echo $_GET['echostr'];
exit;
}