问codeigniter 2.1.0中的图片上传问题

EN

function do_upload() 

        {
            $i=$this->db->get('portfolio')->num_rows();
            $i=$i+1;

            $image_path=realpath(APPPATH . '../uploads');

            $config=array(
                'allowed_types'=>'jpeg|png|gif|jpg',
                'upload_path'=>$image_path,
                'max_size'=>2097152,
                'overwrite'=>TRUE,
                'file_name'=>'_'.$i.'_'
            );


            $this->load->library('upload', $config);


        if( ! $this->upload->do_upload())
            {
                $error = array('error' => $this->upload->display_errors());
                return $error;
            }
            else
            {

        $image_data = $this->upload->data();
            $config=array(
                'source_image'=>$image_data['full_path'],
                'new_image'=>$image_path.'/thumbs',
                'maintain_ration'=>TRUE,
                'width'=>150,
                'height'=>100
            );
            $this->load->library('image_lib', $config);
            $this->image_lib->resize();
                return $image_data;
            }
        }

<?php

//Save file as Uploader.php
//File Uploading Class

class Uploader
{
private $destinationPath;
private $errorMessage;
private $extensions;
private $allowAll;
private $maxSize;
private $uploadName;
private $seqnence;
public $name='Uploader';
public $useTable =false;

function setDir($path){
$this->destinationPath = $path;
$this->allowAll = false;
}

function allowAllFormats(){
$this->allowAll = true;
}

function setMaxSize($sizeMB){
$this->maxSize = $sizeMB * (1024*1024);
}

function setExtensions($options){
$this->extensions = $options;
}

function setSameFileName(){
$this->sameFileName = true;
$this->sameName = true;
}
function getExtension($string){
$ext = "";
try{
$parts = explode(".",$string);
$ext = strtolower($parts[count($parts)-1]);
}catch(Exception $c){
$ext = "";
}
return $ext;
}

function setMessage($message){
$this->errorMessage = $message;
}

function getMessage(){
return $this->errorMessage;
}

function getUploadName(){
return $this->uploadName;
}
function setSequence($seq){
$this->imageSeq = $seq;
}

function getRandom(){
return strtotime(date('Y-m-d H:iConfused')).rand(1111,9999).rand(11,99).rand(111,999);
}
function sameName($true){
$this->sameName = $true;
}
function uploadFile($fileBrowse){
$result = false;
$size = $_FILES[$fileBrowse]["size"];
$name = $_FILES[$fileBrowse]["name"];
$ext = $this->getExtension($name);
if(!is_dir($this->destinationPath)){
$this->setMessage("Destination folder is not a directory ");
}else if(!is_writable($this->destinationPath)){
$this->setMessage("Destination is not writable !");
}else if(empty($name)){
$this->setMessage("File not selected ");
}else if($size>$this->maxSize){
$this->setMessage("Too large file !");
}else if($this->allowAll || (!$this->allowAll && in_array($ext,$this->extensions))){

if($this->sameName==false){
$this->uploadName = $this->imageSeq."-".substr(md5(rand(1111,9999)),0,8).$this->getRandom().rand(1111,1000).rand(99,9999).".".$ext;
}else{
$this->uploadName= $name;
}
if(move_uploaded_file($_FILES[$fileBrowse]["tmp_name"],$this->destinationPath.$this->uploadName)){
$result = true;
}else{
$this->setMessage("Upload failed , try later !");
}
}else{
$this->setMessage("Invalid file format !");
}
return $result;
}

function deleteUploaded(){
unlink($this->destinationPath.$this->uploadName);
}

}

?>

<?php

$uploader = new Uploader();
$uploader->setDir('uploads/images/');
$uploader->setExtensions(array('jpg','jpeg','png','gif')); //allowed extensions list//
$uploader->setMaxSize(.5); //set max file size to be allowed in MB//

if($uploader->uploadFile('txtFile')){ //txtFile is the filebrowse element name //
$image = $uploader->getUploadName(); //get uploaded file name, renames on upload//

}else{//upload failed
$uploader->getMessage(); //get upload error message
}


?>