从opencart里面抠出来一个数据缓存类，看着感觉不错

class cache {
var $maxlifetime = 3600;

function cache() {
if (!is_writable(DIR_CACHE)) {
exit('Error: Could not write to cache directory!');
}

foreach (glob(DIR_CACHE . 'cache.*') as $file) {
$array = explode('.', end(explode('/', $file)));

if ($array[2] < time()) {
$this->delete($array[1]);
}
}
}

function set($key, $value) {
$this->delete($key);

$file = fopen(DIR_CACHE . 'cache.' . $key . '.' . (time() + $this->maxlifetime), 'a');

fwrite($file, serialize($value));
fclose($file);
}

function get($key) {
foreach (glob(DIR_CACHE . 'cache.' . $key . '.*') as $cache) {
$contents = fopen($cache, 'r');
$result = fread($contents, filesize($cache));
fclose($contents);

return unserialize($result);
}
}

function delete($key) {
foreach (glob(DIR_CACHE . 'cache.' . $key . '.*') as $file) {
unlink($file);
}
}
}