PHP: 如何检查图像文件是否存在?

我需要看看我的 cdn 上是否存在一个特定的图像。

我试过以下方法,但没有效果:

if (file_exists(http://www.example.com/images/$filename)) {
echo "The file exists";
} else {
echo "The file does not exist";
}

即使图像存在或不存在,它总是说“文件存在”。我不知道为什么它不工作..。

324015 次浏览

Try like this:

$file = '/path/to/foo.txt'; // 'images/'.$file (physical path)


if (file_exists($file)) {
echo "The file $file exists";
} else {
echo "The file $file does not exist";
}

You need the filename in quotation marks at least (as string):

if (file_exists('http://www.mydomain.com/images/'.$filename)) {
… }

Also, make sure $filename is properly validated. And then, it will only work when allow_url_fopen is activated in your PHP config

A thing you have to understand first: you have no files.
A file is a subject of a filesystem, but you are making your request using HTTP protocol which supports no files but URLs.

So, you have to request an unexisting file using your browser and see the response code. if it's not 404, you are unable to use any wrappers to see if a file exists and you have to request your cdn using some other protocol, FTP for example

You can use the file_get_contents function to access remote files. See http://php.net/manual/en/function.file-get-contents.php for details.

Read first 5 bytes form HTTP using fopen() and fread() then use this:

DEFINE("GIF_START","GIF");
DEFINE("PNG_START",pack("C",0x89)."PNG");
DEFINE("JPG_START",pack("CCCCCC",0xFF,0xD8,0xFF,0xE0,0x00,0x10));

to detect image.

if (file_exists('http://www.mydomain.com/images/'.$filename)) {}

This didn't work for me. The way I did it was using getimagesize.

$src = 'http://www.mydomain.com/images/'.$filename;


if (@getimagesize($src)) {

Note that the '@' will mean that if the image does not exist (in which case the function would usually throw an error: getimagesize(http://www.mydomain.com/images/filename.png) [function.getimagesize]: failed) it will return false.

public static function is_file_url_exists($url) {
if (@file_get_contents($url, 0, NULL, 0, 1)) {
return 1;
}


return 0;
}

If the file is on your local domain, you don't need to put the full URL. Only the path to the file. If the file is in a different directory, then you need to preface the path with "."

$file = './images/image.jpg';
if (file_exists($file)) {}

Often times the "." is left off which will cause the file to be shown as not existing, when it in fact does.

Well, file_exists does not say if a file exists, it says if a path exists. ⚡⚡⚡⚡⚡⚡⚡

So, to check if it is a file then you should use is_file together with file_exists to know if there is really a file behind the path, otherwise file_exists will return true for any existing path.

Here is the function i use :

function fileExists($filePath)
{
return is_file($filePath) && file_exists($filePath);
}

You have to use absolute path to see if the file exists.

$abs_path = '/var/www/example.com/public_html/images/';
$file_url = 'http://www.example.com/images/' . $filename;


if (file_exists($abs_path . $filename)) {


echo "The file exists. URL:" . $file_url;


} else {


echo "The file does not exist";


}

If you are writing for CMS or PHP framework then as far as I know all of them have defined constant for document root path.

e.g WordPress uses ABSPATH which can be used globally for working with files on the server using your code as well as site url.

Wordpress example:

$image_path = ABSPATH . '/images/' . $filename;
$file_url = get_site_url() . '/images/' . $filename;


if (file_exists($image_path)) {


echo "The file exists. URL:" . $file_url;


} else {


echo "The file does not exist";


}

I'm going an extra mile here :). Because this code would no need much maintenance and pretty solid, I would write it with as shorthand if statement:

$image_path = ABSPATH . '/images/' . $filename;
$file_url = get_site_url() . '/images/' . $filename;


echo (file_exists($image_path))?'The file exists. URL:' . $file_url:'The file does not exist';

Shorthand IF statement explained:

$stringVariable = ($trueOrFalseComaprison > 0)?'String if true':'String if false';

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';
}

There is a major difference between is_file and file_exists.

is_file returns true for (regular) files:

Returns TRUE if the filename exists and is a regular file, FALSE otherwise.

file_exists returns true for both files and directories:

Returns TRUE if the file or directory specified by filename exists; FALSE otherwise.


Note: Check also this stackoverflow question for more information on this topic.

Here is the simplest way to check if a file exist:

if(is_file($filename)){
return true; //the file exist
}else{
return false; //the file does not exist
}

try this :

if (file_exists(FCPATH . 'uploads/pages/' . $image)) {
unlink(FCPATH . 'uploads/pages/' . $image);
}

file_exists reads not only files, but also paths. so when $filename is empty, the command would run as if it's written like this:

file_exists("http://www.example.com/images/")

if the directory /images/ exists, the function will still return true.

I usually write it like this:

// !empty($filename) is to prevent an error when the variable is not defined
if (!empty($filename) && file_exists("http://www.example.com/images/$filename"))
{
// do something
}
else
{
// do other things
}

file_exists($filepath) will return a true result for a directory and full filepath, so is not always a solution when a filename is not passed.

is_file($filepath) will only return true for fully filepaths

If you are using curl, you can try the following script:

function checkRemoteFile($url)
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
// don't download content
curl_setopt($ch, CURLOPT_NOBODY, 1);
curl_setopt($ch, CURLOPT_FAILONERROR, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
if(curl_exec($ch)!==FALSE)
{
return true;
}
else
{
return false;
}

}

Reference URL: https://hungred.com/how-to/php-check-remote-email-url-image-link-exist/

you need server path with file_exists

for example

if (file_exists('/httpdocs/images/'.$filename)) {echo 'File exist'; }

If path to your image is relative to the application root it is better to use something like this:

function imgExists($path) {
$serverPath = $_SERVER['DOCUMENT_ROOT'] . $path;


return is_file($serverPath)
&& file_exists($serverPath);
}

Usage example for this function:

$path = '/tmp/teacher_photos/1546595125-IMG_14112018_160116_0.png';


$exists = imgExists($path);


if ($exists) {
var_dump('Image exists. Do something...');
}

I think it is good idea to create something like library to check image existence applicable for different situations. Above lots of great answers you can use to solve this task.

if(@getimagesize($image_path)){
...}

Is working for me.

Here is one function that I use to check any kind of URL. It will check response code is URL exists or not.

/*
* Check is URL exists
*
* @param  $url           Some URL
* @param  $strict        You can add it true to check only HTTP 200 Response code
*                        or you can add some custom response code like 302, 304 etc.
*
* @return string or NULL
*/
function is_url_exists($url, $strict = false)
{
if (is_int($strict) && $strict >= 100 && $strict < 600 || is_array($strict)) {
if(is_array($strict)) {
$response = $strict;
} else {
$response = [$strict];
}
} else if ($strict === true || $strict === 1) {
$response = [200];
} else {
$response = [200,202,301,302,303];
}
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_NOBODY, 1);
curl_setopt($ch, CURLOPT_FAILONERROR, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$return = curl_exec($ch);
if (!curl_errno($ch) && $return !== false) {
return ( in_array(curl_getinfo($ch, CURLINFO_HTTP_CODE), $response) !== false );
}
return false;
}

This is exactly what you need.

Try it:

$imgFile = 'http://www.yourdomain.com/images/'.$fileName;
if (is_file($imgFile) && file_exists($imgFile)) {
echo 'File exists';
} else {
echo 'File not exist';
}

Another Way:

$imgFile = 'http://www.yourdomain.com/images/'.$fileName;
if (is_file($imgFile)) {.....
}