如何在php中访问类函数的配置php值(多维数组)

class Config {
    private $configValues;

    public function __construct() {
        // 初始化配置值
        $this->configValues = [
            'database' => [
                'host' => 'localhost',
                'username' => 'root',
                'password' => 'password',
                'database' => 'mydb'
            ],
            'email' => [
                'host' => 'smtp.example.com',
                'username' => 'user@example.com',
                'password' => 'emailpassword'
            ]
        ];
    }

    public function getConfigValue($section, $key) {
        if (isset($this->configValues[$section][$key])) {
            return $this->configValues[$section][$key];
        } else {
            return null;
        }
    }
}

$config = new Config();

// 获取数据库主机名配置值
$databaseHost = $config->getConfigValue('database', 'host');
echo "Database Host: " . $databaseHost . "<br>";

// 获取电子邮件用户名配置值
$emailUsername = $config->getConfigValue('email', 'username');
echo "Email Username: " . $emailUsername . "<br>";