cache演示函数

<?
ob_start();
$filename="www.html";
$cachetime=3;
function cache($filename,$cachetime){
if(file_exists($filename)&&filemtime($filename)>(time()-$cachetime)){
$handle=fopen($filename,"r");
flock($handle,LOCK_SH);
$data=fread($handle,filesize($filename));
fclose($handle);
echo $data;
}else{
echo rand(1,2222222);
$data=ob_get_contents();
touch($filename);
$handle=fopen($filename,"wb");
flock($handle,LOCK_EX);
fwrite($handle,$data);
fclose($handle);

}
}
cache($filename,$cachetime);
?>