解释如何在PHP中使用简单的路由系统

Question

Hello everybody I am new with Routing systems in Php. Searching on the web I have found this short code for explain how routing should work but... I cannot understand in which way It routes my request to the desired page:

<?php

// Get the requested path with $_SERVER['REDIRECT_URL'],
// and require the page you want to display. I have '' and '/' for both url.com/ and url.com.

// REDIRECT_URL returns normal url e.g. /review,
// in the other hand REQUEST_URI returns including query string e.g. /review?page=4

$request = $_SERVER['REDIRECT_URL'];

switch ($request) {
    case '/' :
        require __DIR__ . '/views/index.php';
        break;

    case '' :
        require __DIR__ . '/views/index.php';
        break;

    case '/about' :
        require __DIR__ . '/views/about.php';
        break;

    default:
        require __DIR__ . '/views/404.php';
        break;
}

When I open it the first time it redirect me to index.php:

<h1>main</h1>

and the other page is about.php:

<h1>about</h1>

My question is: how can I switch to about.php using the routing system?

Because If I write inside the url localhost/simpleRouter/views/about.php it looks like I am bypassing the routing system.... so I cannot figure out how can I use it properly to switch between pages. Morover, the index.php page shows me MAIN and this is good, but i receive a the following:

Notice: Undefined index: REDIRECT_URL in D:\App\xAMPP\htdocs\studio\Php\SviluppareInPHP7\CAP7\simpleRouter\index.php on line 9

Thank you for answering my questions and helping me to improve my knowledge on this field.

Answer 1

You are looking for URL Rewriting. You can configure your Webserver (Apache, NGinx, ...) to redirect all or some requests, e.g. to your router.php.

Apache URL Rewriting
NGinx URL Rewriting

In your router.php, you can then extract the originally requested URL, e.g. about.php. Note that this is different to the views/about.php. The "Router" then includes the specified file. This allows you to use arbitrary URLs instead of filenames.

Also check out the difference between REDIRECT_URL and REQUEST_URL here.