缓存静态页面类

/** * 缓存静态页面类 */class HtmlCache{     /**     * 开启缓存     * $filename缓存完整路径     * $time缓存时间单位是秒，默认7200秒     */    public function cache_start($filename,$time=7200)    {        $cachefile = $filename;        $cachetime = $time;        ob_start();        if(file_exists($cachefile) && (time()-$cachetime < filemtime($cachefile)))//判断文件是否存在或者是否在缓存时间内        {            include($cachefile);            ob_end_flush();            exit;        }      }    /**     * 结束缓存     * $filename缓存完整路径     */    public function cache_end($filename){        $cachefile = $filename;        $fp = fopen($cachefile, 'w');        fwrite($fp, ob_get_contents());        fclose($fp);        ob_end_flush();      }}用法:$HtmlCache = new HtmlCache();$filename = "./cache.html";$HtmlCache->cache_start($filename);    //以下是输出的内容，放在cache_start和cache_end两个方法之间    echo "cache";$HtmlCache->cache_end($filename);