PHP 使用raw格式發送post請求

function http_post($url, $data_string) {
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
            'X-AjaxPro-Method:ShowList',
            'Content-Type: application/json; charset=utf-8',
            'Content-Length: ' . strlen($data_string))
    );
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
    $data = curl_exec($ch);
    curl_close($ch);
    return $data;
}

$url = '';
            $postData =array(
                'username => $params['username'],
                
            );
            http_post($url,json_encode($postData));