PHP Composer报404错误：请求URL未找到问题求助

Alright, let's troubleshoot that 404 error you're hitting when accessing localhost/hello/foo with Slim 3 and Apache. Here's a step-by-step breakdown to get your endpoint working:

1. Verify Your File Structure & Apache Modules #

First, double-check your core setup:

• Make sure your index.php is located in /var/www/html/hello/ (since you're accessing localhost/hello/...). If it's directly in /var/www/html/, your target URL should be localhost/foo instead.
• Ensure your index.php has complete Slim initialization code (your snippet was truncated). A minimal working example looks like this:

  <?php
  use \Psr\Http\Message\ServerRequestInterface as Request;
  use \Psr\Http\Message\ResponseInterface as Response;
  
  // Adjust the path to autoload.php based on your composer setup
  require 'vendor/autoload.php';
  
  $app = new Slim\App();
  
  // Define your route to match your desired URL
  $app->get('/foo', function (Request $request, Response $response) {
      $response->getBody()->write("Hello from Foo!");
      return $response;
  });
  
  $app->run();
  

• Enable Apache's mod_rewrite module (critical for Slim's URL routing) with these commands:

  sudo a2enmod rewrite
  sudo systemctl restart apache2
  

2. Configure .htaccess & Apache Site Settings #

Slim relies on URL rewriting to route all requests to index.php, so you need a proper .htaccess file:

• Create (or update) .htaccess in /var/www/html/hello/ with this content:

  RewriteEngine On
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^ index.php [QSA,L]
  

• Update your Apache site configuration (usually at /etc/apache2/sites-available/000-default.conf) to allow .htaccess overrides. Find the <Directory /var/www/html> block and modify it to:

  <Directory /var/www/html>
      Options Indexes FollowSymLinks MultiViews
      AllowOverride All
      Require all granted
  </Directory>
  

• Restart Apache again to apply changes:

  sudo systemctl restart apache2
  

3. Confirm Composer Dependencies Are Installed #

Head to your /var/www/html/hello/ directory and run:

composer install

This ensures the slim/slim package and all required dependencies are installed (you should see a vendor directory after this completes).

4. Check Route-to-URL Matching #

A common mistake is mismatched routes and URLs:

• If your index.php is in /var/www/html/hello/, the routes you define are relative to localhost/hello/. So a route $app->get('/foo', ...) maps directly to localhost/hello/foo (which is what you're trying to access).
• If you had defined a route like $app->get('/hello/foo', ...), you'd need to access localhost/hello/hello/foo—which doesn't exist, hence the 404.

内容的提问来源于stack exchange，提问作者Frakcool