PHP5图片上传代码，日期文件夹，随机文件名

PHP5图片上传代码，日期文件夹，随机文件名

index.htm

<form enctype="multipart/form-data" action="upload.php" method="post">
<input type="hidden" name="MAX_FILE_SIZE" value="2000000">
<input name="userfile" type="file">　　
<input type="submit" value="上传文件">
</form>

upload.php

<?
$f=$_FILES[jeff_img_upload];

//有没有传文件判断
if ($f[error]==4){
echo("<script>alert(请选择你要上传的文件，谢谢！);location.href=index.htm;</script>");
}
else{
//出错判断
if ($f[error]){
echo "失败，文件太大了！错误代码是".$f[error];
exit;
}

//类型判断
if (substr($f[type], 0, 5) == image) {
                    switch ($f[type]) {
                        case image/jpeg:
                        case image/jpg:
                        case image/pjpeg:
                            $ext = .jpg;
                            break;
                        case image/gif:
                            $ext = .gif;
                            break;
                        case image/png:
                        case image/x-png:
                            $ext = .png;
                            break;
                        default:
                            header(Content-type: text/html; charset=UTF-8);
                            echo("<script>alert(你传的不是图片吧？);location.href=index.htm;< /script>");
                            die(REDIRECTING...);
                            break;
                    }
}else {
                    header(Content-type: text/html; charset=UTF-8);
                    echo("<script>alert(你传的不是图片吧？);location.href=index.htm;</script>");
                    die(REDIRECTING...);
                }

//生成随机数
$randomnum=NULL;
for($j=0;$j<=5;$j++)//随机数字的长度，本例随机数长度为6
{
srand((double)microtime()*1000000);
$randomnumber=rand(!$j ? 1: 0,9);//产生随机数，不以0为第一个数，有些特殊的地方0开头被系统省略
$randomnum.=$randomnumber;
}


$dest_dir=/var/www/htdocs/upload;//设定上传目录

//生成日期目录。先判断日期目录是否存在，不存在则创建它。
if(!file_exists(date("Ymd"))){
mkdir(date("Ymd"),0777);}


$dest=$dest_dir./.date("Ymd")./.time()._.$randomnum.$ext;//设置文件名为时间戳加上随机数避免重复
$r=move_uploaded_file($f[tmp_name],$dest);
chmod($dest, 0777);//设定上传的文件的属性
}
echo "成功了，文件地址是：".$dest;
?>