Android Studio（Hybride App）+ XAMPP-LocalHost无法POST提取-400错误请求

Question

我正在使用Android Studio创建自己的（混合）应用程序，因此我正在使用HTML，CSS和Javascript。我还使用XAMPP创建LocalHost，并使用phpMyAdmin创建了数据库。我尝试使用javascript上的访存来连接数据库，但每次都会收到400错误请求。

那是我的dtbs.php

// --- Add Notitie

if (strcasecmp($_GET['m'], 'addNote') == 0) {

    if (!$conn) {
        $response['code'] = 0;
        $response['status'] = $api_response_code[$response['code']]['HTTP Response'];
        $response['data'] = mysqli_connect_error();

    } else {
        $response['code'] = 0;
        $response['status'] = $api_response_code[$response['code']]['HTTP Response'];

        $lQuery = "INSERT INTO notes (Note_ID, Title, Notitie) VALUES (NULL, '". $postvars['title'] . "'," . $postvars['notitie'].")";


        $result = $conn -> query($lQuery);
        $rows = array();
        if (!$result) {
            $response['data'] = "db error";
        } else {

            while ($row = $result -> fetch_assoc()) {
                $rows[] = $row;
            }



            $response['code'] = 1;
            $response['status'] = $api_response_code[$response['code']]['HTTP Response'];
            $response['data'] = $rows;

        }
    }
}  

在我的JavaScript中，我添加了以下内容：

//Create connection with dtbs

let apiAddress = "http://localhost/wm/dtbs.php?";
    let opties = {
        method: "POST", // *GET, POST, PUT, DELETE, etc.
        mode: "cors", // no-cors, *cors, same-origin
        cache: "no-cache", // *default, no-cache, reload, force-cache, only-if-cached
        credentials: "omit", // include, *same-origin, omit
        headers: {
            "Content-Type": "application/json",
            "Accept": "application/json"
        }
    }

//Creating function for connecting to DTB and GET or PUT data.
//Put title and text into dtbs
    function addNote() {


        let url = apiAddress + "m=addNote";
        // onze php api verwacht een paar parameters
        // we voegen deze toe aan de body van de opties

        // body data type must match "Content-Type" header
        opties.body = JSON.stringify({
            title: document.getElementById("makenewtitle").value,
            notitie: document.getElementById("makenewnote").value,
            format: "json"
        });

        // test de api
        fetch(url, opties)
            .then(function(response) {
                return response.json();
            })
            .then(function(responseData){

                // de verwerking van de data
                var list = responseData.data;


            })
            .catch(function(error) {
                // verwerk de fout
                var alert = document.getElementById("alert")
                alert.innerHTML = "fout : " + error;
            });
    }

有人可以帮我吗？

提前谢谢

That is what I get when I try to put title and text in my database