//获取AccessToken
  function getAccessToken(){
    $appid="你的appid";
    $appsecret = "你的appsecret";
    //文件存储
    $data=json_decode(get_php_file("access_token.php"));
    if($data->expire_time<time()){
      $url="https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$appid."&secret=".$appsecret;
      $res=json_decode(httpGet($url));
      $access_token=$res->access_token;
      if($access_token){
        $data->expire_time=time()+7000;
        $data->access_token=$access_token;
        set_php_file("access_token.php",json_encode($data));
      }
    }else{
      $access_token=$data->access_token;
    }
    return $access_token;
  }