无法在 PHP 错误中重新声明 class

Cannot redeclare class in PHP error

PHP 的新手。使用 SLIM 框架和路由已经过测试并且工作正常。有两个文件 index.php 和 API.php。 index.php 是:

<?php

require 'vendor/autoload.php';
require_once 'API.php';

//Turn on error checking
ini_set('display_errors',1);
ini_set('display_startup_errors',1);
error_reporting(-1);

//Create a new SLIM app
$app = new \Slim\Slim();
$app->response->headers->set('Content-Type', 'application/json');


$app->get('/', function() use($app) { 
    $app->response->setStatus(200);
    echo "InstaAPI\n";
});

$app->run();

?>

API 是:

<?php

class DbHandler{

    protected static $conn;

    function __construct() {

        //Static self notation is different
        if(!isset(self::$conn)) {
            //same as self.connect
            $this->connect();
        }

    }

    function __destruct(){

        if(isset(self::$conn)){

            self::$conn->close();
        }

    }


    function connect(){

        $config = parse_ini_file('../../config2.ini');

        // Try and connect to the database
        self::$conn = mysqli_connect('localhost',$config['username'],$config['password'],$config['dbname']);

        if(self::$conn===FALSE) {

            header("HTTP/1.1 500 Internal Server Error");
            header("Content-Type: application/json");
            $response = array("Response"=>"Failed to connect to the database");
            echo json_encode($response);
            die();

        }

        else{

            echo "Fine!!";
        }

    }//end connect


}//end class


?>

我收到错误:PHP Fatal error: Cannot redeclare class DbHandler in ../API.php on line 62。不知道为什么会这样。我正在使用 require_once,但仍然出现相同的错误。有人可以指点我可能做错了什么吗?

Api.php的代码少于62行。看起来下面有额外的代码。考虑删除多余的行