php检查外部doman上是否存在文件（访问子域） [英] php check if file exists on an external doman (accessing form a sub domain)

问题描述

我在 http://www.reelfilmlocations.co.uk 上有一个网站

上述网站有一个管理区域，上传图片并在uploads / images目录的子文件夹中创建不同大小的副本。

The above site has an admin area where images are uploaded and different size copies created in subfolders of an uploads/images directory.

我创建一个移动设备的网站，它将在子域操作，但使用主域中的数据库和图像
http：//2012.reelfilmlocations.co.uk

I am creating a site for mobile devices, which will operate on a sub-domain, but use the database and images from the main domain, http://2012.reelfilmlocations.co.uk

我想要能够访问父域，我可以通过链接到具有完整域的图像做的http：www.reelfilmlocations.co.uk/images/minidisplay/myimage.jpg

I want to be able to access the images that are on the parent domain, which i can do by linking to the image with the full domain i.e http:www.reelfilmlocations.co.uk/images/minidisplay/myimage.jpg

虽然我需要检查图像是否存在第一...

Though i need to check if the image exists first...

我有一个php函数检查图像是否存在，如果它返回图像的完整url 。

I have a php function that checks if the images exists, if it does it returns the full url of the image.

如果它不存在，我想返回一个占位符图像的路径。

If it doesn't exist i want to return the path of a placeholder image.

函数，如果存在，返回正确的图像，但如果不存在，它只是返回到占位符图像所在的目录的路径，即 http://www.reelfilmlocations.co。 uk / images / thumbs / 。没有no-image.jpg位。

The following function i have, returns the correct image if it exists, but if it doesn't, it is just returning the path to the directory where the placeholder image resides i.e http://www.reelfilmlocations.co.uk/images/thumbs/. without the no-image.jpg bit.

问题的页面是： http：//2012.reelfilmlocations.co.uk/browse-unitbases/
我在我的页面上获得图像的代码是：

The page in question is: http://2012.reelfilmlocations.co.uk/browse-unitbases/ the code i have on my page to get the image is:

<img src="<?php checkImageExists('/uploads/images/thumbs/', $row_rs_locations['image_ubs']);?>">

我的PHP功能：

if(!function_exists("checkImageExists")){
    function checkImageExists($path, $file){
        $imageName = "http://www.reelfilmlocations.co.uk".$path.$file;
        $header_response = get_headers($imageName, 1);
        if(strpos($header_response[0], "404" ) !== false ){
            // NO FILE EXISTS
            $imageName = "http://www.reelfilmlocations.co.uk".$path."no-image.jpg"; 
        }else{
            // FILE EXISTS!!
            $imageName = "http://www.reelfilmlocations.co.uk".$path.$file;
        }
        echo($imageName);   
    }
}

无法让这个工作，我做了一些挖掘并阅读关于curl的一些帖子：

Failing to get this to work i did some digging around and read some posts about curl:

这只是每次都返回一个占位符图片。

This just returns a placeholder image everytime.

if(!function_exists("remoteFileExists")){
    function remoteFileExists($url) {
        $curl = curl_init($url);

        //don't fetch the actual page, you only want to check the connection is ok
        curl_setopt($curl, CURLOPT_NOBODY, true);

        //do request
        $result = curl_exec($curl);

        $ret = false;

        //if request did not fail
        if ($result !== false) {
            //if request was ok, check response code
            $statusCode = curl_getinfo($curl, CURLINFO_HTTP_CODE);  
            if ($statusCode == 200 ) {
                $ret = true;   
            }
        }
        curl_close($curl);

        return $ret;
    }
}

if(!function_exists("checkImageExists")){
    function checkImageExists($path, $file){
        $imageName = "http://www.reelfilmlocations.co.uk".$path.$file;

        $exists = remoteFileExists($imageName);
        if ($exists){
            // file exists do nothing we already have the correct $imageName
        } else {
                    // file does not exist so set our image to the placeholder
            $imageName = "http://www.reelfilmlocations.co.uk".$path."no-image.jpg";   
        }
            echo($imageName);
    }
}

我不知道是否可以a 403，或如何检查是否是这种情况。

I dont know if it could be to do with getting a 403, or how to check if this is the case.

任何指针或东西，我可以尝试woud非常感激。

any pointers or things i could try woud be greatly appreciated.

推荐答案

我会使用CURL，发出HEAD请求并检查响应代码。

I'd do it using CURL, issuing a HEAD request and checking the response code.

，但应该做的诀窍：

 $URL = 'sub.domain.com/image.jpg';
 $res = `curl  -s -o /dev/null -IL -w "%{http_code}" http://$URL`;
 if ($res == '200')
     echo 'Image exists';

上面的代码将填充 $ res 申请的状态代码（注意，我不要在 $ URL 中包含 http：//

The code above will populate $res with status code of the requisition (pay attention that I DON'T include the http:// prefix to the $URL variable because I do it in the command line.

当然，使用PHP的CURL函数也可以获得同样的效果，上面的调用可能无法在你的服务器上工作。只是说明如果我有同样的需要我会做什么。

Of course the same might be obtained using PHP's CURL functions, and the above call might not work on your server. I am just explaining what I'd be doing if I had the same need.

这篇关于php检查外部doman上是否存在文件（访问子域）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！