如何使用 PHP 检查远程文件是否存在？

if (false === file_get_contents("http://example.com/path/to/image")) {
$image = $default_image;
}

Should work ;)

You can instruct curl to use the HTTP HEAD method via CURLOPT_NOBODY.

More or less

$ch = curl_init("http://www.example.com/favicon.ico");


curl_setopt($ch, CURLOPT_NOBODY, true);
curl_exec($ch);
$retcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
// $retcode >= 400 -> not found, $retcode = 200, found.
curl_close($ch);

Anyway, you only save the cost of the HTTP transfer, not the TCP connection establishment and closing. And being favicons small, you might not see much improvement.

Caching the result locally seems a good idea if it turns out to be too slow. HEAD checks the time of the file, and returns it in the headers. You can do like browsers and get the CURLINFO_FILETIME of the icon. In your cache you can store the URL => [ favicon, timestamp ]. You can then compare the timestamp and reload the favicon.

Don't know if this one is any faster when the file does not exist remotely, is_file(), but you could give it a shot.

$favIcon = 'default FavIcon';
if(is_file($remotePath)) {
$favIcon = file_get_contents($remotePath);
}

You should issue HEAD requests, not GET one, because you don't need the URI contents at all. As Pies said above, you should check for status code (in 200-299 ranges, and you may optionally follow 3xx redirects).

The answers question contain a lot of code examples which may be helpful: PHP / Curl: HEAD Request takes a long time on some sites

As Pies say you can use cURL. You can get cURL to only give you the headers, and not the body, which might make it faster. A bad domain could always take a while because you will be waiting for the request to time-out; you could probably change the timeout length using cURL.

Here is example:

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;
}


$exists = remoteFileExists('http://stackoverflow.com/favicon.ico');
if ($exists) {
echo 'file exists';
} else {
echo 'file does not exist';
}

A radical solution would be to display the favicons as background images in a div above your default icon. That way, all overhead would be placed on the client while still not displaying broken images (missing background images are ignored in all browsers AFAIK).

There's an even more sophisticated alternative. You can do the checking all client-side using a JQuery trick.

$('a[href^="http://"]').filter(function(){
return this.hostname && this.hostname !== location.hostname;
}).each(function() {
var link = jQuery(this);
var faviconURL =
link.attr('href').replace(/^(http:\/\/[^\/]+).*$/, '$1')+'/favicon.ico';
var faviconIMG = jQuery('<img src="favicon.png" alt="" />')['appendTo'](link);
var extImg = new Image();
extImg.src = faviconURL;
if (extImg.complete)
faviconIMG.attr('src', faviconURL);
else
extImg.onload = function() { faviconIMG.attr('src', faviconURL); };
});

From http://snipplr.com/view/18782/add-a-favicon-near-external-links-with-jquery/ (the original blog is presently down)

CoolGoose's solution is good but this is faster for large files (as it only tries to read 1 byte):

if (false === file_get_contents("http://example.com/path/to/image",0,null,0,1)) {
$image = $default_image;
}

This is not an answer to your original question, but a better way of doing what you're trying to do:

Instead of actually trying to get the site's favicon directly (which is a royal pain given it could be /favicon.png, /favicon.ico, /favicon.gif, or even /path/to/favicon.png), use google:

<img src="http://www.google.com/s2/favicons?domain=[domain]">

Done.

This can be done by obtaining the HTTP Status code (404 = not found) which is possible with file_get_contents^Docs making use of context options. The following code takes redirects into account and will return the status code of the final destination (Demo):

$url = 'http://example.com/';
$code = FALSE;


$options['http'] = array(
'method' => "HEAD",
'ignore_errors' => 1
);


$body = file_get_contents($url, NULL, stream_context_create($options));


foreach($http_response_header as $header)
sscanf($header, 'HTTP/%*d.%*d %d', $code);


echo "Status code: $code";

If you don't want to follow redirects, you can do it similar (Demo):

$url = 'http://example.com/';
$code = FALSE;


$options['http'] = array(
'method' => "HEAD",
'ignore_errors' => 1,
'max_redirects' => 0
);


$body = file_get_contents($url, NULL, stream_context_create($options));


sscanf($http_response_header[0], 'HTTP/%*d.%*d %d', $code);


echo "Status code: $code";

Some of the functions, options and variables in use are explained with more detail on a blog post I've written: HEAD first with PHP Streams.

function remote_file_exists($url){
return(bool)preg_match('~HTTP/1\.\d\s+200\s+OK~', @current(get_headers($url)));
}
$ff = "http://www.emeditor.com/pub/emed32_11.0.5.exe";
if(remote_file_exists($ff)){
echo "file exist!";
}
else{
echo "file not exist!!!";
}

If you are dealing with images, use getimagesize. Unlike file_exists, this built-in function supports remote files. It will return an array that contains the image information (width, height, type..etc). All you have to do is to check the first element in the array (the width). use print_r to output the content of the array

$imageArray = getimagesize("http://www.example.com/image.jpg");
if($imageArray[0])
{
echo "it's an image and here is the image's info<br>";
print_r($imageArray);
}
else
{
echo "invalid image";
}

You can use :

$url=getimagesize(“http://www.flickr.com/photos/27505599@N07/2564389539/”);


if(!is_array($url))
{
$default_image =”…/directoryFolder/junal.jpg”;
}

PHP's inbuilt functions may not work for checking URL if allow_url_fopen setting is set to off for security reasons. Curl is a better option as we would not need to change our code at later stage. Below is the code I used to verify a valid URL:

$url = str_replace(' ', '%20', $url);
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if($httpcode>=200 && $httpcode<300){  return true; } else { return false; }

Kindly note the CURLOPT_SSL_VERIFYPEER option which also verify the URL's starting with HTTPS.

all the answers here that use get_headers() are doing a GET request. It's much faster/cheaper to just do a HEAD request.

To make sure that get_headers() does a HEAD request instead of a GET you should add this:

stream_context_set_default(
array(
'http' => array(
'method' => 'HEAD'
)
)
);

so to check if a file exists, your code would look something like this:

stream_context_set_default(
array(
'http' => array(
'method' => 'HEAD'
)
)
);
$headers = get_headers('http://website.com/dir/file.jpg', 1);
$file_found = stristr($headers[0], '200');

$file_found will return either false or true, obviously.

A complete function of the most voted answer:

function remote_file_exists($url)
{
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_NOBODY, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1); # handles 301/2 redirects
curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
if( $httpCode == 200 ){return true;}
}

You can use it like this:

if(remote_file_exists($url))
{
//file exists, do something
}

You could use the following:

$file = 'http://mysite.co.za/images/favicon.ico';
$file_exists = (@fopen($file, "r")) ? true : false;

Worked for me when trying to check if an image exists on the URL

To check for the existence of images, exif_imagetype should be preferred over getimagesize, as it is much faster.

To suppress the E_NOTICE, just prepend the error control operator (@).

if (@exif_imagetype($filename)) {
// Image exist
}

As a bonus, with the returned value (IMAGETYPE_XXX) from exif_imagetype we could also get the mime-type or file-extension with image_type_to_mime_type / image_type_to_extension.

This works for me to check if a remote file exist in PHP:

$url = 'https://cdn.sstatic.net/Sites/stackoverflow/img/favicon.ico';
$header_response = get_headers($url, 1);


if ( strpos( $header_response[0], "404" ) !== false ) {
echo 'File does NOT exist';
} else {
echo 'File exists';
}

You can use the filesystem: use Symfony\Component\Filesystem\Filesystem; use Symfony\Component\Filesystem\Exception\IOExceptionInterface;

and check $fileSystem = new Filesystem(); if ($fileSystem->exists('path_to_file')==true) {...

If the file is not hosted external you might translate the remote URL to an absolute Path on your webserver. That way you don't have to call CURL or file_get_contents, etc.

function remoteFileExists($url) {


$root = realpath($_SERVER["DOCUMENT_ROOT"]);
$urlParts = parse_url( $url );


if ( !isset( $urlParts['path'] ) )
return false;


if ( is_file( $root . $urlParts['path'] ) )
return true;
else
return false;


}


remoteFileExists( 'https://www.yourdomain.com/path/to/remote/image.png' );

Note: Your webserver must populate DOCUMENT_ROOT to use this function

If you're using the Symfony framework, there is also a much simpler way using the HttpClientInterface:

private function remoteFileExists(string $url, HttpClientInterface $client): bool {
$response = $client->request(
'GET',
$url //e.g. http://example.com/file.txt
);


return $response->getStatusCode() == 200;
}

The docs for the HttpClient are also very good and maybe worth looking into if you need a more specific approach: https://symfony.com/doc/current/http_client.html

If you're using the Laravel framework or guzzle package, there is also a much simpler way using the guzzle client, it also works when links are redirected:

$client = new \GuzzleHttp\Client(['allow_redirects' => ['track_redirects' => true]]);
try {
$response = $client->request('GET', 'your/url');
if ($response->getStatusCode() != 200) {
// not exists
}
} catch (\GuzzleHttp\Exception\GuzzleException $e) {
// not exists
}

More in Document : https://docs.guzzlephp.org/en/latest/faq.html#how-can-i-track-redirected-requests

Please check this URL. I believe it will help you. They provide two ways to overcome this with a bit of explanation.

Try this one.

// Remote file url
$remoteFile = 'https://www.example.com/files/project.zip';


// Initialize cURL
$ch = curl_init($remoteFile);
curl_setopt($ch, CURLOPT_NOBODY, true);
curl_exec($ch);
$responseCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);


// Check the response code
if($responseCode == 200){
echo 'File exists';
}else{
echo 'File not found';
}

or visit the URL

https://www.codexworld.com/how-to/check-if-remote-file-exists-url-php/#:~:text=The%20file_exists()%20function%20in,a%20remote%20server%20using%20PHP.