<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;   } www.1sucai.cn  //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);