Cache js or css files

Hi guys..
I have big problem about caching js or css files.

which should i use, using http header or just direct to js or css files.

for example, i have controllers to load one or multiple js files and caching using http headers: 

PHP Code:

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class asset_feed extends CI_Controller 
{
    public function script()
    {
        if (ENVIROTMENT === 'development') {
            session_write_close();
        }
        
        $this->output->set_header('Content-Type: text/javascript; charset=UTF-8');
        $this->output->set_header('Expires: ' . gmdate('D, d M Y H:i:s', time() + 3600) . ' GMT');
        
        if (! empty($_GET['scripts']) && is_array($_GET['scripts'])) {
            $data = '';
            foreach ($_GET['scripts'] as $script) {
                $script_name = 'assets/js';
                $path = explode("/", $script);
                foreach ($path as $index => $filename)
                    if (preg_match("@^[\w][\w\.-]+$@", $filename))
                        $script_name .= DIRECTORY_SEPARATOR . $filename;
                
                if (preg_match("@\.js$@", $script_name) && is_readable($script_name)) {
                    
                    $data .= read_file($script_name);
                    $data .= ";\n\n";
                }
            }
            
            $this->output->append_output($data);
        }
    }
} 


and in my view files:

Code:

<script type="text/javascript" src="http://localhost:8000/asset_feed/script?scripts[]=file1.js&scripts[]=file2.js"></script>

or like this: 

Code:

<script type="text/javascript" src="http://localhost:8000/assets/js/file1.js"></script>
<script type="text/javascript" src="http://localhost:8000/assets/js/file2.js"></script>

please some one to teach me..