Simple file cache

cache.php

<?php

class Cache {

	function __construct( $format = '' ) {

		$this->format = $format;
		$this->cache_life = '1200';
		$this->cache_file = 'cache/' . md5( $_SERVER['REQUEST_URI'] );;
		// check exists....
		$this->get_cache();

	}

	function put_cache( $data ) {
		file_put_contents( $this->cache_file, $data );
		$this->do_output( $data );
	}

	function get_cache() {

		$filemtime = @filemtime( $this->cache_file );
		if ( $filemtime && ( time() - $filemtime < $this->cache_life ) ) {
			$this->do_output( file_get_contents( $this->cache_file ) );
			die();
		}
		@unlink( $this->cache_file );
	}

	function do_output ( $data ) {
		header('Cache-Control: no-cache, must-revalidate');
		header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
		header('Content-type: application/json');
		echo $data;
	}
}