php后台直接获取code

function get_code()
{
    $appid = 'wx2323232322222';
    $url = $this->get_url();

    $redirect_uri = urlencode($url);
    //获取code后，请求以下链接获取access_token：
    $oauth2_url = "https://open.weixin.qq.com/connect/oauth2/authorize?appid=" . $appid . "&redirect_uri=" . $redirect_uri . "&response_type=code&scope=snsapi_base&state=123#wechat_redirect";

    header("location: $oauth2_url");
}
function get_url()
{
    //$url = $this->GetCurUrl();
    return 'https://www.b.com';//回调地址
}
function GetCurUrl(){
    $url = 'http://';
    if (isset ($_SERVER ['HTTPS']) && $_SERVER ['HTTPS'] == 'on') {
        $url = 'https://';
    }

    $url .= $_SERVER ['HTTP_HOST'] . $_SERVER ['REQUEST_URI'];

    // 兼容后面的参数组装
    if (stripos($url, '?') === false) {
        $url .= '?t=' . time();
    }

    return $url;
}
get_url 返回链接在微信里面打开会得到code