thinkphp下载基于Http解决思路

public static function Download($Download){
    import("Com.Buyback.QueryAmazon"); 
    import("ORG.Net.Http"); 
    $bookInformModel =M("admin"); 
    $result = $bookInformModel->where("Download='$Download'")->select();
    if($result[0]['image'] == ""){
    $data['id'] = $result[0]['id'];
    $remoteUrl = QueryAmazon::getImage($Download); 
    if(!empty($remoteUrl['ImageURL'])){
    $localUrl = "oa/Tpl/Public/Upload/".$Download.".jpg";
    Http::curl_download($remoteUrl['ImageURL'], "./".$localUrl);
    }else{
    $localUrl = "oa/Tpl/Public/Upload/";
    }
    $data['image'] = $localUrl;
    $bookInformModel->save($data);
    return $localUrl;
} 
return $result[0]['image'];
} 

点击下载的时候
下载
不能下载 求解释