php中用session文件计算在线人数

php中session记录在文件中,每个session对应一个文件.

通过对文件的计算,可以得到当前的在线人数

<?php

ob_start();

session_start();

$num=0;

$dirpt    =    "online";

$reftime    =    1;

if (is_dir($dirpt) && $dir = opendir($dirpt)) {

  while (($file = readdir($dir)) !== false) {

    if(strcmp($file,"..")==0 || strcmp($file,".")==0){

        continue;

    }

    $D_[date("Y-m-d H:i:s",filemtime($dirpt."/".$file))]=$file;

    $num++;

    unset($cum);

  } 

  closedir($dir);

  $filename    =    session_id();

  $fp        =    fopen($dirpt."/".$filename,"w");

  fputs($fp,"");

  fclose($fp);

  $ntime    =    date("Y-m-d H:i:s",mktime(date("H"),date("i")-1,0,date("m"),date("d"),date("Y")));

  $D_[$ntime]="-";

  krsort($D_);

  $onlinenumber=0;

  while(1){

    $vkey=key($D_);

    $onlinenumber++;

    if(strcmp($ntime,$vkey)==0){

        break;

    }else{

        array_shift($D_);

    }

  }

  array_shift($D_);

  reset($D_);

  while(count($D_)>0){

    $ckey=key($D_);

    unlink($dirpt."/".$D_[$ckey]);

    if(!next($D_)){

        break;

    }

  }

}else{

    @chmod("..",0777);

    @mkdir($dirpt,0777);

}

$online=$onlinenumber-1;

$retime=60*$reftime;

echo "document.write('当前在线<strong><font color=red>$online</font></strong>人<meta http-equiv=refresh content="{$retime},url=">')";

ob_end_flush();

?>