A quick and dirty PHP class to cache JSON data

Cache.php

<?php

const MONTH = "Y-m"; // 2000-01
const DAY = "Y-m-d"; // 2000-01-01
const HALF_DAY = "Y-m-d-A"; // 2000-01-01-AM
const HOUR = "Y-m-d-H"; // 2000-01-01-24
const MINUTE = "Y-m-d-H-i"; // 2000-01-01-24-60

class Cache {

    private $directory;
    private $lifespan;

    public function __construct($directory, $lifespan) {
        $this->directory = $directory;
        $this->lifespan = $lifespan;

        if(!is_dir("$directory/.")) {
            mkdir($directory, 0777, true);
        }
    }

    /**
     * Add data to the cache
     *
     * @param string $json The JSON data to store
     * @param boolean $clearCache Whether or not to remove other files inside the cache when adding data
     * @return void
     */
    public function addData($json, $clearCache = true) {
        if($clearCache) $this->clearCache();
        file_put_contents("$this->directory/{$this->generateDate()}.json", $json);
    }

    /**
     * Check cache data
     *
     * @return boolean Returns true if the data in the cache is up to date, false if it needs to be updated
     */
    public function checkCache() {
        return file_exists("$this->directory/{$this->generateDate()}.json");
    }

    /**
     * Get cache data
     *
     * @return string A string of JSON data from the cache
     */
    public function getCache() {
        return file_get_contents("$this->directory/{$this->generateDate()}.json");
    }

    /**
     * Clear cache
     *
     * @return void
     */
    public function clearCache() {
        array_map("unlink", glob("$this->directory/*.json"));
    }

    /**
     * Generate cache date
     *
     * @return string An up-to-date file name to store and check cache files against
     */
    private function generateDate() {
        return (new DateTime)->format($this->lifespan);
    }

}

Sample usage:

require_once "Cache.php";
$cache = new Cache("cache/api/items", HALF_DAY); // create a directory at cache/api/items that will last half a day

$items;
if($cache->checkCache()) {
    $items = $cache->getCache();
} else {
    $items = "[1,2,3,4,5]"; // however you get the JSON data you want to cache
    $cache->addData($items);
}

echo $items;