求一个php数据缓存类，谢谢！

[nihailai]

求一个php数据缓存类，谢谢！
有例子更好啊

[hmzhmz]

$data = "这是需要缓存的数据";
$filename = "filename";
$cache = new Data_cache($filename,$data);

[hmzhmz]

<?php
class Data_cache
{
	//缓存文件存放的地址
   private $file = "/usr/www/program/cache/";
   
   //文件的名称
   private $filename = "filename";
   
   //需要写入缓存文件的数据
   private $data = "";
   
   public function __construct($filename,$data)
   {
   		$this->filename = $filename;
   		$this->data = $data;
   		
   		if($this->judge_cache_file_exists())
   		{
   			$this->put_data_to_file();
   		}
   }
   
   //写入缓存文件
   public function put_data_to_file($data)
   {
   		if(isset($data))
   		{
   			$dir = $file.md5($filename).".php";
   			
   			file_put_contents($dir,$this->data);
   		}else{
   			return FALSE;
   		}
   }
   
   //判断缓存文件是否存在
   public function judge_cache_file_exists()
   {
   		return file_get_contents($file.md5($filename).".php",$this->data);
   }
}



?>