一个强大的PHP缓存类(9)

                return null;//was expired you need to create new
            }
        }
        
        //returns the filename for the cache
        private function fileName($key){
            return $this->cache_path.md5($key);
        }
    //////////END Cache for files individually///////////////////
    
    //////////Cache for APP variables///////////////////
    
        //load variables from the file
        private function APP_start ($app_file='application'){
            $this->application_file=$app_file;      
            
            if (file_exists($this->cache_path.$this->application_file)){ // if data file exists, load the cached variables
                //erase the cache every X minutes
                $app_time=filemtime($this->cache_path.$this->application_file)+$this->cache_expire;
                if (time()>$app_time){
                    $this->addLog('deleting APP file: '.$this->cache_path.$this->application_file);
                    unlink ($this->cache_path.$this->application_file);//erase the cache
                }
                else{//not expired
                    $filesize=filesize($this->cache_path.$this->application_file);
                    if ($filesize>0){
                        $file = fopen($this->cache_path.$this->application_file, 'r');// read data file
                        if ($file){
                            $this->addLog('reading APP file: '.$this->cache_path.$this->application_file);
                            $data = fread($file, $filesize);
                            fclose($file);
                            $this->application = unserialize($data);// build application variables from data file
                        }//en if file could open
                    }//end if file size
                
                }    
            }
            else  {//if the file does not exist we create it
                $this->addLog('creating APP file: '.$this->cache_path.$this->application_file);