Comment obtenir toutes les catégories de produits de la base de données mysql via php et renvoyer le tableau json

Pour le côté php, voici comment vous pouvez obtenir le tableau des catégories et créer json, pour les instructions préparées, voici comment vous pouvez accomplir

$success = false;
try {

  $DBH = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
$success = true;
}
catch(PDOException $e) {
$response["success"] = 0;
$response["message"] = 'Connection failed: ' . $e->getMessage();
$response["data"]=null;
die(json_encode($response));
}

$query_categories = "SELECT category_name FROM categories";

try{

$sth = $sth->prepare($query_categories );
$success = true;

} catch(PDOException $e) {
$response["success"] = 0;
$response["message"] = 'Prepare failed: ' . $e->getMessage();
$response["data"]=null;
die(json_encode($response));
}

try{
$sth->execute();
$success = true;
} catch(PDOException $e) {
$response["success"] = 0;
$response["message"] = 'Execute failed: ' . $e->getMessage();
$response["data"]=null;
die(json_encode($response));
}

$categories = $sth->fetchAll(PDO::FETCH_COLUMN, 0);/* fetches all categories from db */

/* Output of $query_categories
Array
(
    [0] => cat1
    [1] => cat2
    [2] => cat3
    [3] => cat4
)
*/
/* json encode $query_categories 
["cat1","cat2","cat3","cat4"]
*/

/* check if categories exist or not*/
if(empty($categories)){
        $response["success"] = 0;
        $response["message"] = "No categories found";
        $response["data"]=null;
        die(json_encode($response));
        $connection = null; 

}

if($success) {
    $response["success"] = 1;
    $response["message"] = "Kylie";
    $response["data"]=$categories;
    die(json_encode($response));
    $connection = null;      
 /* output
 {"success":0,"message":"Kylie","data":["cat1","cat2","cat3","cat4"]}
 */
} else {
    $response["success"] = 2;/* don't where you are setting success to 2*/
    $response["message"] = "something went wrong";
    $response["data"]=null;
    die(json_encode($response));
    $connection = null;
}

} else {
        $response["success"] = 3;/* don't where you are setting success to 3*/
        $response["message"] = "Another brick in the wall";  
        $response["data"]=null; 
        die(json_encode($response));
        $connection = null;
}

Je ne suis pas bon en java mais voici la référence Comment parser un JSON et transformer ses valeurs en tableau ?

/* store json string in  the_json */
JSONObject myjson = new JSONObject(the_json);
JSONArray the_json_array = myjson.getJSONArray("data");

Objets de données PHP