<form method="post" action="suo_do.php"  enctype="multipart/form-data">        <input type="file" name="pic" />        <input type="submit" value="上传1" />         </form>                                <?php        header("content-type:text/html;charset=gbk");        ini_set("date.timezone","Asia/chong");        //判断文件是否为空        if(empty($_FILES)){            echo"上传文件过大";            exit;        }        //判断文件上传是否有错误        if($_FILES['pic']['error']){            echo "上传文件";            exit;        }        //判断文件类型是否非法获取文件后缀        $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 "上传文件非法";            exit;        }        $file=date('YmdHis').rand().".".$ex;        $src=$_FILES['pic']['tmp_name'];        $des="upload/".$file;        $rs=move_uploaded_file($src,$des);                        //缩略图        //读取已经上传图片        $image=imagecreatefromjpeg($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;        }        //创建空白新图片        $newimage=imagecreatetruecolor($width, $height);        //copy源图片内容 copy新图片        imagecopyresized($newimage, $image, 0,0, 0,0, $width, $height, $w, $h);        $filename="upload/s_".$file;        imagejpeg($newimage,$filename);