取自ThinkPHP的文件缓存类代码，这里就不多废话了，小伙伴们自己看注释吧。

<?php  /**   * @desc 文件缓存   */  class Cache{    const C_FILE = "/Runtime/";    private $dir = "";    const EXT = ".tpl";    private $filename = "";    public function __construct($dir = ""){      $this->dir = $dir;          }    /**     *  @desc 设置文件缓存     *  @param string $key 文件名      *  @param unkonw $data 缓存数据     *  @param int  $expire 过期时间     */    public function set($key,$data,$expire = 0){      $this->filename =   dirname(__FILE__).self::C_FILE.$this->dir.$key.self::EXT;      if(file_exists($this->filename)){        $res = $this->get($key);        if(md5($res) == md5(json_encode($data) ) ){          return true;        }      }      if(!is_dir(dirname($this->filename))){        mkdir(dirname($this->filename),0777);      }            $source = fopen($this->filename,"w+");      fwrite($source,json_encode($data));      fclose($source);    }        /**     *  @desc 获取文件     * @param string $key 文件名     */    public function get($key){      //$filename = dirname(__FILE__).self::C_FILE.$this->dir.$key.self::EXT;      if(!file_exists($this->filename)){        return "缓存文件已经不存在";      }else{        $res = file_get_contents($this->filename);      }      return $res;    }    /**     *  @desc 删除文件     * @param string $key 文件名     */    public function del($key){      unlink($this->filename);    }      }    $data = array("name"=>"song","age"=>20,"sex"=>"man","favority"=>array("apple","banana"));  $cache = new Cache();  $cache->set("cache",$data);  //$cache->get("cache");  //$cache->del("cache");