略微加速

<?php
$path = './tupian/';
$limit = 300000;
$filename = $_FILES['tupian']['name'];
$size = $_FILES['tupian']['size'];
if ($size > $limit)
    exit('<script type="text/javascript">alert("文件太大！");history.back();</script>');
$typelimit = array('jpeg','jpg','gif','bmp','gif');
function type($filename) //获取文件后缀名函数
{
    return substr(strrchr($filename, '.'), 1);
}
$type = type($filename);
if(!in_array($type, $typelimit))
{
    echo '<script type="text/javascript">alert("文件类型不正确！！");history.back();</script>';
    exit;
}
$time = time();
$newname = $time.".".$type;
$lj = $path.$newname;
while (file_exists($lj)) 
{
    $time = time()+1;
    $newname = $time.".".$type;
    $lj = $path.$newname;
}
move_uploaded_file($_FILES['tupian']['tmp_name'],$lj);
echo "上传成功";
?>