ミニプログラムメッセージプッシュ構成の場合

<?php
define("TOKEN","100txy");// 后台填写的token
$wechatObj = new wechatAPI();
$wechatObj->isValid();
class wechatAPI
{
  public function isValid()//验证微信接口，如果确认是微信就返回它传来的echostr参数
  {
     $echoStr = $_GET["echostr"];
     if ($this->checkSignature()) {
     echo $echoStr;
     exit;
     }
  }
  private function checkSignature(){ //官方的验证函数
   $signature = $_GET["signature"];
   $timestamp = $_GET["timestamp"];
   $nonce = $_GET["nonce"];
   $token = TOKEN;
   $tmpArr = array($token, $timestamp, $nonce);
   sort($tmpArr, SORT_STRING);
   $tmpStr = implode( $tmpArr );
   $tmpStr = sha1( $tmpStr );
   if( $tmpStr == $signature ){
   return true;
   }else{
   return false;
   }
  }
};