业务需要写了个在PHP5+UTF8开发环境下的文件上传类,可支持多文件上传,并对常用文件的类型进行MIME检测,当然还有些功能没有加上去,如自动更名,图片处理等.可根据需要自己添加，看下面的代码吧：

USE:

$up = new upfile(ROOT_PATH.'data/'.date("Ym",time()),array('gif','jpg','jpeg'),true);
$fileimg = $up->upload($_FILES['img']);//返回上传后文件名数组,$_FILES['img']为上传的文件
可使用$up->log查看上传时信息.

<?php
//====================================================
// FileName: upfile.class.php
// Summary: 文件上传类
//====================================================
if(!defined('OK'))exit(__FILE__.'Access Denied');
class upfile {
public $ExtensionFileFormat = array();
public $returninfo = array();

private $ImageFileFormat = array('gif','bmp','jpg','jpe','jpeg','png');
private $OtherFileFormat = array('zip','pdf','rar','xls','doc','ppt','csv');
private $savePath;
private $attachment_path = './upfiles/';
private $overwrite = false; # 同名时是否覆盖
private $maxSize = 0; # 文件最大字节，为0时不限制大小
private $ext;
private $errno = 0;

/* 构造函数
* (string)$savePath 文件保存路径，默认为$attachment_path
* (array)$extensionFileFormat 自定义上传文件的扩展名，未设置时为$ImageFileFormat || $OtherFileFormat
* (bool)$overwrite 是否覆盖同名文件
*/
public function __construct($savePath='',$extensionFileFormat = array(),$overwrite = false) {
$this->savePath = empty($savePath)?$this->attachment_pathsavePath.'/';
$this->extensionFileFormat = is_array($extensionFileFormat)?$extensionFileFormat:array();
$this->overwrite = is_bool($overwrite)?$overwrite:false;
}

/*上传函数
* (array)$files 待上传的文件数组$_FILES['attach']
* (number)$maxSize 文件的最大字节数，默认为0不限制上传大小
*/
public function upload($files,$maxSize=0) {
$this->maxSize = is_numeric($maxSize)?$maxSize:0;
if(isset($files) && is_array($files)) {
if(is_array($files['name'])) {
foreach($files as $key => $var) {
foreach($var as $id => $val) {
$attachments[$id][$key] = $val;
}
}
} else {
$attachments[] = $files;
}
}
self::check_file_type($attachments);
if(empty($this->filelist)) {
$this->log .= "待上传的文件列表为空。\n";
return array();
}
if(!self::makeDirectory() || !@is_writable($this->savePath)) {
$this->log .= $this->savePath . "不能创建或其权限为不可写。\n";
return array();
}
$filearray = array();
foreach($this->filelist as $k=>$f) {
if($this->maxSize && $f['size']>$this->maxSize) {
$this->log .= $f['name'] . "其大小超过了设定的值：" . $this->maxSize ."\n";
}elseif($this->overwrite == false && file_exists($this->savePath . $f['name'])) {
$this->log .= $f['name'] . "已经存在于目录：" . $this->savePath . "\n";
}else{
@unlink($this->savePath . $f['name']);
if(@move_uploaded_file($f['tmp_name'],$this->savePath . mb_convert_encoding($f['name'],'gbk','utf-8'))) {//如果不进行编码转换，中文将无法支持
$this->log .= $f['name'] . "成功上传到目录：". $this->savePath ."\n";
$filearray[$k] = $this->savePath . $f['name'];
}else{
$this->log .= $f['name'] . "上传失败。\n";
}
}
}
return $filearray;
}