一个强大的PHP缓存类(8)

    //end overloads
    
    //////////Cache for files individually///////////////////
    
        //creates new cache files with the given data, $key== name of the cache, data the info/values to store
        private function put($key, $data){
            if ( $this->get($key)!= $data ){//only write if it's different
                $values = serialize($data);
                $filename = $this->fileName($key);
                $file = fopen($filename, 'w');
                if ($file){//able to create the file
                    $this->addLog('writting key: '.$key.' file: '.$filename);
                    fwrite($file, $values);
                    fclose($file);
                }
                else  $this->addLog('unable to write key: '.$key.' file: '.$filename);
            }//end if different
        }
        
        //returns cache for the given key
        private function get($key){
            $filename = $this->fileName($key);
            if (!file_exists($filename) || !is_readable($filename)){//can't read the cache
                $this->addLog('can\'t read key: '.$key.' file: '.$filename);
                return null;
            }
            
            if ( time() < (filemtime($filename) + $this->cache_expire) ) {//cache for the key not expired
                $file = fopen($filename, 'r');// read data file
                if ($file){//able to open the file
                    $data = fread($file, filesize($filename));
                    fclose($file);
                    $this->addLog('reading key: '.$key.' file: '.$filename);
                    return unserialize($data);//return the values
                }
                else{
                    $this->addLog('unable to read key: '.$key.' file: '.$filename);
                    return null;
                }
            }
            else{
                $this->addLog('expired key: '.$key.' file: '.$filename);
                unlink($filename);