php 图片上传类代码，功能也比较全，大家根据需要选择。

先来个简单的：

 
<? 
//http://www.jb51.net 
class upLoad{ 
public $length; //限定文件大小 
public $file; //判断此类是用于图片上传还是文件上传 
public $fileName; //文件名 
public $fileTemp; //上传临时文件 
public $fileSize; //上传文件大小 
public $error; //上传文件是否有错,php4没有 
public $fileType; //上传文件类型 
public $directory; // 
public $maxLen; 
public $errormsg; 
function __construct($length,$file=true,$directory) 
{ 
$this->maxLen=$length; 
$this->length=$length*1024; 
$this->file=$file; //true为一般文件，false为图片的判断 
$this->directory=$directory; 
} 
public function upLoadFile($fileField) 
{ 
$this->fileName=$fileField['name']; 
$this->fileTemp=$fileField['tmp_name']; 
$this->error=$fileField['error']; 
$this->fileType=$fileField['type']; 
$this->fileSize=$fileField['size']; 
$pathSign = DIRECTORY_SEPARATOR; // / 
if($this->file) //一般文件上传 
{ 
$path = $this->_isCreatedDir($this->directory);//取得路径 
if($path)//http://www.jb51.net 
{ 
$createFileType = $this->_getFileType($this->fileName);//设置文件类别 
$createFileName=uniqid(rand()); //随机产生文件名 
$thisDir=$this->directory.$pathSign.$createFileName.".".$createFileType; 
if(@move_uploaded_file($this->fileTemp,$thisDir)) //把临时文件移动到规定的路径下 
{ 
return $thisDir; 
} 
} 
}else{ //图片上传 
$path = $this->_isCreatedDir($this->directory);//取得路径 
if($path)//路径存在//http://www.jb51.net 
{ 
$createFileType = $this->_getFileType($this->fileName);//设置文件类别 
$createFileName=uniqid(rand()); 
return @move_uploaded_file($this->fileTemp,$this->directory.$pathSign.$createFileName.".".$createFileType) ? true : false; 
} 
} 
} 
public function _isBig($length,$fsize) //返回文件是否超过规定大小 
{ 
return $fsize>$length ? true : false; 
} 
public function _getFileType($fileName) //获得文件的后缀 
{ 
return end(explode(".",$fileName)); 
} 
public function _isImg($fileType) //上传图片类型是否允许 
{ 
$type=array("jpeg","gif","jpg","bmp"); 
$fileType=strtolower($fileType); 
$fileArray=explode("/",$fileType); 
$file_type=end($fileArray); 
return in_array($file_type,$type);//http://www.jb51.net 
} 
public function _isCreatedDir($path) //路径是否存在，不存在就创建 
{ 
if(!file_exists($path)) 
{ 
return @mkdir($path,0755)?true:false; //权限755// 
} 
else 
{ 
return true; 
} 
} 
public function showError() //显示错误信息 
{//http://www.jb51.net 
echo "<Script Language ='JavaScript'>\n history.back();\n alert(' $this->errormsg');\n </Script> \n"; 
exit(); 
} 
} 
class multiUpLoad extends upLoad{ 
public $FILES; 
function __construct($arrayFiles,$length,$file=true,$directory) 
{ 
$this->FILES=$arrayFiles; 
parent::__construct($length,$file,$directory); 
} 
function upLoadMultiFile() 
{ 
$arr=array(); 
if($this->_judge()||$this->_judge()=="no") //文件全部符合规格,就开始上传 
{ 
foreach($this->FILES as $key=>$value) 
{ 
$strDir=parent::upLoadFile($this->FILES[$key]); 
array_push($arr, $strDir); 
} 
//http://www.jb51.net 
return $arr; 
}else 
{ 
return false; 
} 
} 
function _judge() 
{ 
if($this->file) 
{ 
foreach($this->FILES as $key=>$value) 
{ 
if($this->_isBig($this->length,$value['size'])) 
{ 
$this->errormsg="文件超过 $this->maxLen K"; 
parent::showError(); 
} 
if($value['error']=UPLOAD_ERR_NO_FILE) 
{ 
//$this->errormsg="上传文件出现错误"; 
//parent::showError(); 
return "no"; 
} 
} 
return true; 
}else 
{ 
//http://www.jb51.net 
foreach($this->FILES as $key=>$value) 
{ 
if($this->_isBig($this->length,$value['size'])) 
{ 
$this->errormsg="图片超过$this->maxLen"; 
parent::showError(); 
} 
if($value['error']!=0) 
{ 
$this->errormsg="上传图片出现错误"; 
parent::showError(); 
} 
if(!$this->_isImg($value['type'])) 
{ 
$this->errormsg="图片格式不对"; 
parent::showError(); 
} 
} 
return true; 
} 
} 
} 
?> 

再来个复杂点的，可以自动生成缩略图的功能的php上传类
开始第一步：
创建文件夹，布局：
annex：附件（该目录下存放上传的原图片）
|― smallimg：存放缩略图片
|― mark：存放水印图片
include：存放类文件，字体（本程序代码使用的是：04B_08__.TTF）
|― upfile.php：集成简单上传，生成缩略图及水印的类文件信息
|― 04B_08__.TTF：字体文件
test.php：测试文件
第二步上传类
upfile.php

 
<?php 
class UPImages { 
var $annexFolder = "annex";//附件存放点，默认为：annex 
var $smallFolder = "smallimg";//缩略图存放路径，注：必须是放在 $annexFolder下的子目录，默认为：smallimg 
var $markFolder = "mark";//水印图片存放处 
var $upFileType = "jpg gif png";//上传的类型，默认为：jpg gif png rar zip 
var $upFileMax = 1024;//上传大小限制，单位是“KB”，默认为：1024KB 
var $fontType;//字体 
var $maxWidth = 500; //图片最大宽度 
var $maxHeight = 600; //图片最大高度 
function UPImages($annexFolder,$smallFolder,$includeFolder) { 
$this->annexFolder = $annexFolder; 
$this->smallFolder = $smallFolder; 
$this->fontType = $includeFolder."/04B_08__.TTF"; 
} 
function upLoad($inputName) { 
$imageName = time();//设定当前时间为图片名称 
if(@empty($_FILES[$inputName]["name"])) die(error("没有上传图片信息，请确认")); 
$name = explode(".",$_FILES[$inputName]["name"]);//将上传前的文件以“.”分开取得文件类型 
$imgCount = count($name);//获得截取的数量 
$imgType = $name[$imgCount-1];//取得文件的类型 
if(strpos($this->upFileType,$imgType) === false) die(error("上传文件类型仅支持 ".$this->upFileType." 不支持 ".$imgType)); 
$photo = $imageName.".".$imgType;//写入数据库的文件名 
$uploadFile = $this->annexFolder."/".$photo;//上传后的文件名称 
$upFileok = move_uploaded_file($_FILES[$inputName]["tmp_name"],$uploadFile); 
if($upFileok) { 
$imgSize = $_FILES[$inputName]["size"]; 
$kSize = round($imgSize/1024); 
if($kSize > ($this->upFileMax*1024)) { 
@unlink($uploadFile); 
die(error("上传文件超过 ".$this->upFileMax."KB")); 
} 
} else { 
die(error("上传图片失败，请确认你的上传文件不超过 $upFileMax KB 或上传时间超时")); 
} 
return $photo; 
} 
function getInfo($photo) { 
$photo = $this->annexFolder."/".$photo; 
$imageInfo = getimagesize($photo); 
$imgInfo["width"] = $imageInfo[0]; 
$imgInfo["height"] = $imageInfo[1]; 
$imgInfo["type"] = $imageInfo[2]; 
$imgInfo["name"] = basename($photo); 
return $imgInfo; 
} 
function smallImg($photo,$width=128,$height=128) { 
$imgInfo = $this->getInfo($photo); 
$photo = $this->annexFolder."/".$photo;//获得图片源 
$newName = substr($imgInfo["name"],0,strrpos($imgInfo["name"], "."))."_thumb.jpg";//新图片名称 
if($imgInfo["type"] == 1) { 
$img = imagecreatefromgif($photo); 
} elseif($imgInfo["type"] == 2) { 
$img = imagecreatefromjpeg($photo); 
} elseif($imgInfo["type"] == 3) { 
$img = imagecreatefrompng($photo); 
} else { 
$img = ""; 
} 
if(empty($img)) return False; 
$width = ($width > $imgInfo["width"]) ? $imgInfo["width"] : $width; 
$height = ($height > $imgInfo["height"]) ? $imgInfo["height"] : $height; 
$srcW = $imgInfo["width"]; 
$srcH = $imgInfo["height"]; 
if ($srcW * $width > $srcH * $height) { 
$height = round($srcH * $width / $srcW); 
} else { 
$width = round($srcW * $height / $srcH); 
} 
if (function_exists("imagecreatetruecolor")) { 
$newImg = imagecreatetruecolor($width, $height); 
ImageCopyResampled($newImg, $img, 0, 0, 0, 0, $width, $height, $imgInfo["width"], $imgInfo["height"]); 
} else { 
$newImg = imagecreate($width, $height); 
ImageCopyResized($newImg, $img, 0, 0, 0, 0, $width, $height, $imgInfo["width"], $imgInfo["height"]); 
} 
if ($this->toFile) { 
if (file_exists($this->annexFolder."/".$this->smallFolder."/".$newName)) @unlink($this->annexFolder."/".$this->smallFolder."/".$newName); 
ImageJPEG($newImg,$this->annexFolder."/".$this->smallFolder."/".$newName); 
return $this->annexFolder."/".$this->smallFolder."/".$newName; 
} else { 
ImageJPEG($newImg); 
} 
ImageDestroy($newImg); 
ImageDestroy($img); 
return $newName; 
} 
function waterMark($photo,$text) { 
$imgInfo = $this->getInfo($photo); 
$photo = $this->annexFolder."/".$photo; 
$newName = substr($imgInfo["name"], 0, strrpos($imgInfo["name"], ".")) . "_mark.jpg"; 
switch ($imgInfo["type"]) { 
case 1: 
$img = imagecreatefromgif($photo); 
break; 
case 2: 
$img = imagecreatefromjpeg($photo); 
break; 
case 3: 
$img = imagecreatefrompng($photo); 
break; 
default: 
return False; 
} 
if (empty($img)) return False; 
$width = ($this->maxWidth > $imgInfo["width"]) ? $imgInfo["width"] : $this->maxWidth; 
$height = ($this->maxHeight > $imgInfo["height"]) ? $imgInfo["height"] : $this->maxHeight; 
$srcW = $imgInfo["width"]; 
$srcH = $imgInfo["height"]; 
if ($srcW * $width > $srcH * $height) { 
$height = round($srcH * $width / $srcW); 
} else { 
$width = round($srcW * $height / $srcH); 
} 
if (function_exists("imagecreatetruecolor")) { 
$newImg = imagecreatetruecolor($width, $height); 
ImageCopyResampled($newImg, $img, 0, 0, 0, 0, $width, $height, $imgInfo["width"], $imgInfo["height"]); 
} else { 
$newImg = imagecreate($width, $height); 
ImageCopyResized($newImg, $img, 0, 0, 0, 0, $width, $height, $imgInfo["width"], $imgInfo["height"]); 
} 
$white = imageColorAllocate($newImg, 255, 255, 255); 
$black = imageColorAllocate($newImg, 0, 0, 0); 
$alpha = imageColorAllocateAlpha($newImg, 230, 230, 230, 40); 
ImageFilledRectangle($newImg, 0, $height-26, $width, $height, $alpha); 
ImageFilledRectangle($newImg, 13, $height-20, 15, $height-7, $black); 
ImageTTFText($newImg, 4.9, 0, 20, $height-14, $black, $this->fontType, $text[0]); 
ImageTTFText($newImg, 4.9, 0, 20, $height-6, $black, $this->fontType, $text[1]); 
if($this->toFile) { 
if (file_exists($this->annexFolder."/".$this->markFolder."/".$newName)) @unlink($this->annexFolder."/".$this->markFolder."/".$newName); 
ImageJPEG($newImg,$this->annexFolder."/".$this->markFolder."/".$newName); 
return $this->annexFolder."/".$this->markFolder."/".$newName; 
} else { 
ImageJPEG($newImg); 
} 
ImageDestroy($newImg); 
ImageDestroy($img); 
return $newName; 
} 
} 
?> 

第三步：测试上传类
test.php

 
<?php 
$annexFolder = "annex"; 
$smallFolder = "smallimg"; 
$markFolder = "mark"; 
$includeFolder = "include"; 
require("./".$includeFolder."/upfile.php"); 
$img = new UPImages($annexFolder,$smallFolder,$includeFolder); 
$text = array("www.jb51.net","all rights reserved"); 
if(@$_GET["go"]) { 
$photo = $img->upLoad("upfile"); 
$img->maxWidth = $img->maxHeight = 350;//设置生成水印图像值 
$img->toFile = true; 
$newSmallImg = $img->smallImg($photo); 
$newMark = $img->waterMark($photo,$text); 
echo "<img src='".$newSmallImg."' border='0'><br><br>"; 
echo "<img src='".$newMark."' border='0'><br><br>"; 
echo "<a href='./test.php'>继续上传</a>"; 
} else { 
?> 
<form method="post" action="./test.php?go=go" enctype="multipart/form-data"> 
<input type="file" name="upfile"><br><br> 
<input type="submit" value="上传"> 
</form> 
<?php 
} 
?>