define("TOKEN","myToken");// 后臺填寫的token，在微信公眾平臺啟用$wechatObj = new wechatAPI();$wechatObj->isValid();class wechatAPI{  public function isValid()//驗證微信接口，驗證函數以外的代碼和微信公眾號開發token設置相同  {     $echoStr = $_GET["echostr"];     if ($this->checkSignature()) {       header('content-type:text');//add，一定要加入header      echo $echoStr;      exit;     }  }  private function checkSignature()  //官方的驗證函數  {     $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;     }  }};