src/Leevel/Http/Request.php
public function getQueryString(): ?string
    {
        $queryString = $this->normalizeQueryString($this->server->get('QUERY_STRING'));

        return '' === $queryString && '0' !== $queryString ? null : $queryString;
    }
public function getQueryString(): ?string
    {
        $queryString = $this->normalizeQueryString($this->server->get('QUERY_STRING'));

        return '' === $queryString && '0' !== $queryString ? null : $queryString;
    }
取回查询参数.

@return null|string