<?php 
$url = $_POST ['url'];
//$url="gallery/ddung/2.jpg";//要下载的图片链接
DownImage($url);

//下载url指向的图片
function DownImage($url) 
{ 
  $mime=getMime($url);
  header("Content-Type: ".$mime);    
  $ext=getExt($url);
  header("Content-Disposition: attachment; filename=".basename($url) );
  header("Content-Transfer-Encoding: binary");
  $fp=file($url);    
  foreach($fp as $fileLine) 
  {
          echo $fileLine;
    }
}

//获取要下载的图片的MIME信息
function getMime($url)
{
  if(preg_match("/\.(jpg|jpeg)$/",$url))
    return "image/jpeg";
  else if(preg_match("/\.(gif)$/",$url))
    return "image/gif";
  else if(preg_match("/\.(png)$/",$url))
    return "image/png";
  else if(preg_match("/\.(bmp)$/",$url))
    return "image/bmp";
  else
    return "err";
}

//获取要下载的图片后缀名
function getExt($url) 
{
    if(preg_match("/\.(jpg|jpeg)$/",$url))
    return "jpg";
  else if(preg_match("/\.(gif)$/",$url))
    return "gif";
  else if(preg_match("/\.(png)$/",$url))
    return "png";
  else if(preg_match("/\.(bmp)$/",$url))
    return "bmp";
  else
    return "err";
}
?>