How to handle PHP URL redirection and route resolution?

PHP is a scripting language widely used for developing websites and web applications. When building a website, URL redirection and route resolution are common requirements, which can provide a better user experience and more friendly URLs. This article will introduce how PHP handles URL redirection and route resolution.

URL redirection refers to the process of forwarding the URL requested by the user to another URL. It can be used to change the page structure of the website or process old URLs to maintain search engine optimization (SEO) and user access continuity. In PHP, you can use the header function to implement URL redirection.

For example, assuming we want to redirect the old URL "/old-page.php" visited by the user to the new URL "/new-page.php", we can use the following code:

header("Location: /new-page.php");
exit;

In this code, the header function is used to set the HTTP Header, set the Location field to a new URL, and then end the execution of the current script through the exit function. In this way, when users visit the old URL, they will be redirected to the new URL.

It should be noted that the header function must be called before any output, otherwise an error will occur. In addition, when using redirection, you should ensure that the new URL is valid and cannot form a circular redirection, which will cause the user to be unable to access the web page.

In addition to URL redirection, route resolution is also one of the important technologies for building excellent websites. Route resolution refers to routing requests to the corresponding handler or page based on different parts of the URL. Through route parsing, friendly URLs can be realized, allowing users to understand the structure of the website more intuitively, and at the same time, different requests can be processed conveniently.

In PHP, you can use regular expressions to parse URLs and determine the actions to be performed based on the matching results. The following is a simple example that shows how to parse the URL and call the corresponding processing function:

$url = $_SERVER['REQUEST_URI'];
$patterns = array(
    '/^/user/(d+)$/' => 'showUser',
    '/^/article/(d+)$/' => 'showArticle',
    // 其他路由规则...
);

foreach ($patterns as $pattern => $action) {
    if (preg_match($pattern, $url, $matches)) {
        array_shift($matches);
        call_user_func_array($action, $matches);
        exit;
    }
}

http_response_code(404);
echo "Page not found";

In this code, the URL requested by the user is first obtained through $_SERVER['REQUEST_URI']. Then some routing rules and corresponding processing functions are defined. By traversing the routing rules, the regular expression is used to match the URL. If the match is successful, the corresponding processing function is called and the matching parameters are passed. Finally, if no rules are matched, a 404 error page is returned.

It should be noted that this is just a simple example and does not solve all routing problems. In practical applications, you can use more powerful routing libraries, such as Symfony's Routing component, to perform route analysis more conveniently.

In summary, URL redirection and route resolution are commonly used technologies when building websites. In PHP, URL redirection can be achieved using the header function, and simple route parsing can be achieved using regular expressions. Through the flexible use of these technologies, the user experience and functionality of the website can be improved.

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