php的页面缓存练习

 <?php
 /*
  * 自定义页面缓存类
  */
 namespace page_cache;
 class Page
 {
     public $CacheRoot = "pageCache/";//缓存文件存放目录,
     public $CacheLimitTime = 0;//缓存文件更新时间，0不更新
     public $CacheFileName = '';//缓存文件名，
     public $CacheFileExt = '.php';//缓存文件扩展名称

     //构造函数,设置缓存更新时间
     public function __construct($CacheLimitTime)
     {
         if(intval($CacheLimitTime))
         {
             $this->CacheLimitTime = $CacheLimitTime;
             $this->CacheFileName = $this->GetFileName();
             ob_start();
             return true;
         }
         else
         {
             return false;
         }
     }

     //检查缓存文件是否在更新时间内，在更新时间内返回文件内容，不在更新时间内返回false
     public function CheckTime()
     {
         if(file_exists($this->CacheFileName))
         {
             if($this->CacheLimitTime +$this->GetFileCreateTime($this->CacheFileName)> time())
             {
                 echo file_get_contents($this->CacheFileName);
                 ob_end_flush();//输出内容到缓冲区
                 exit();
             }
         }
         return false;
     }

     /*
      * 创建缓存文件
      * param $cacheFileName; type string; value 自定义缓存文件的名称
      */
     public function CreateCacheFile($cacheFileName='')
     {
         $getCacheContent = ob_get_contents();
         ob_end_flush ();
         if(!empty($cacheFileName))
         {
            return  $this->SaveFile($cacheFileName,$getCacheContent);
         }
         else
         {
             return $this->SaveFile($this->CacheFileName,$getCacheContent);
         }
     }

     /*
      * 清除缓存
      * param $fileName;type string;value all;note:value is all,clear all cache;
      */
     public function ClearCache($fileName = "all")
     {
         if($fileName!='all')
         {
             $fileName = $this->CacheRoot.strtoupper(md5($fileName)).$this->CacheFileExt;
             if(file_exists($fileName))
             {
                 return @unlink($fileName);
             }
             else
             {
                 return false;
             }
         }
         if($fileName = 'all')
         {
             if(is_dir(($this->CacheRoot)))
             {
                if($dir = opendir($this->CacheRoot))
                {
                    while($file = readdir($dir))
                    {
                        if(!is_dir($file))
                        {
                            unlink($this->CacheRoot.$file);
                        }

                    }
                    closedir($dir);
                    return true;
                }
             }
             else
             {
                 return false;
             }
         }
     }
     //获取缓存的文件名称
     public function GetFileName()
     {
         return $this->CacheRoot.strtoupper(md5($_SERVER['REQUEST_URI'])).$this->CacheFileExt;
     }

     //返回缓存文件上次修改的时间
     public function GetFileCreateTime($filename)
     {
         if(!trim($filename)) return 0;
         if(file_exists($filename))
         {
             return intval(filemtime($filename));
         }
         else
         {
             return 0;
         }
     }

     //保存文件并写入内容
     public function SaveFile($filename,$text)
     {
         if(empty($filename)||empty($text))
         {
             return false;
         }
         if($this->CacheDir(dirname($filename)))
         {
             if($fp = fopen($filename,"w"))
             {
                 if(fwrite($fp,$text))
                 {
                     fclose($fp);
                     return true;
                 }
                 else
                 {
                     fclose($fp);
                     return false;
                 }
             }
         }

     }

     //创建缓存目录
     public function CacheDir($dir,$mode="0777")
     {
         if(empty($dir))
         {
             return false;
         }
         $dir = str_replace("\\","/",$dir);

         $dir = explode("/",$dir);

         $mkdir = '';
         foreach($dir as $val)
         {
             $mkdir .= $val.'/';
             if($val=='./'||$val=='../'||$val=="")
             {
                 continue;
             }
             if(!file_exists($mkdir))
             {
                 if(!@mkdir($mkdir,$mode))
                 {
                     return false;
                 }
             }
         }

         return true;

     }

 }

 $cache = new Page(30);
 $cache->CheckTime();
 echo "Now is : " . date ( "Y-m-d H:i:s" ,time());
 $cache ->CreateCacheFile();