<form method="post" action="suo_do.php" enctype="multipart/form-data">  
<input type="file" name="pic" />  
<input type="submit" value="上傳1" />  
</form>  
<?php  
header("content-type:text/html;charset=gbk");  
ini_set("date.timezone","Asia/chong");  
//判斷文件是否為空  
if(empty($_FILES)){  
echo"上傳文件過大";  
exit;  
}  
//判斷文件上傳是否有錯(cuò)誤  
if($_FILES['pic']['error']){  
echo "上傳文件";  
exit;  
}  
//判斷文件類型是否非法獲取文件后綴  
$allowtype=array("jpg","png","jpeg","gif");  
$a=explode('.',$_FILES['pic']['name']);  
$index=count($a)-1;  
$ex=strtolower($a[$index]);  
if(!in_array($ex,$allowtype)){  
echo "上傳文件非法";  
exit;  
}  
$file=date('YmdHis').rand().".".$ex;  
$src=$_FILES['pic']['tmp_name'];  
$des="upload/".$file;  
$rs=move_uploaded_file($src,$des);  

//縮略圖  
//讀取已經(jīng)上傳圖片  
$image=imagecreatefromjpeg($des);  
$a=getimagesize($des);  
$w=$a[0];  
$h=$a[1];  
if($w>$h){  
$width=300;  
$height=$width/$w*$h;  
}else if($w<$h){  
$height=300;  
$width=$height/$h*$w;  
}else{  
$width=300;  
$height=300;  
} www.dhdzp.com 
//創(chuàng)建空白新圖片  
$newimage=imagecreatetruecolor($width, $height);  
//copy源圖片內(nèi)容 copy新圖片  
imagecopyresized($newimage, $image, 0,0, 0,0, $width, $height, $w, $h);  
$filename="upload/s_".$file;  
imagejpeg($newimage,$filename);