PHP：实现类

Question

当我在我的类中实现接口时，autoloader首先获取带有命名空间的接口类，并且包含它没有问题。但是它得到没有命名空间的接口类名​​，所以我的自动加载器不能包含这些文件，我有错误。 我的班级：

namespace model\order;
use lib\model as Lib;
class Bitgo implements Lib\BitcoinInterface
{

}

自动加载机：

<?php
Class Autoloader
{
public function __construct()
{
    spl_autoload_register(array($this, 'mainAutoload'));
}

public function mainAutoload ($className)
{
    var_dump(__DIR__);
    if ($className) {
        $fullPath = $this->checkPathExist($className);

        require_once ($fullPath);

        $this->checkClassExist($className);
    }
}

private function checkPathExist($className) {

    $pathClass = str_replace(['_', '\\'], '/', $className);
    $fullPath  = URL_APP  . $pathClass . '.php';

    if (file_exists($fullPath)) {
        return $fullPath;
    }

    $fullPath = strtolower($fullPath);
    if (file_exists($fullPath)) {
        return $fullPath;
    }

    if (SYSTEM_DEBUG_MODE) {
        exit('Error: file not exists - ' . $fullPath);
    }
    $error = 'System error! Please report to email: info@bit-changer.net';
    Lib_logger::saveToLog($error . ' (Path: '.$fullPath.')', LOG_TYPE_ERROR_CRITICAL);
    exit($error);
}

private function checkClassExist($className) {

    if (class_exists($className)) {
        return;
    }

    if (strripos($className, '\\') > 0) {
        $delimPos = strripos($className, '\\');
        $className = substr($className, $delimPos + 1, strlen($className));
    }

    if (!class_exists($className)) {
        if (SYSTEM_DEBUG_MODE) {
            exit('Error: class not exists - ' . $className);
        }
        $error = 'System error! Please report to email: info@bit-changer.net';
        Lib_logger::saveToLog($error . ' (Class: '.$className.')', LOG_TYPE_ERROR_CRITICAL);
        exit($error);
    }
}
}


new Autoloader();