PHP检查文件是否在不同域名上的存在情况

PHP检查文件是否在不同域名下的存在情况

Earlier today I needed to find out if a file exists on a different domain. Initially I used the file_exists function, but then when that threw back an error I remembered that file_exists only checks whether a file or directory exists on the same server as the script.

After I played around with various functions, I came up with a few lines of code that actually works:

How to check if file exists on a different domain

$image = "http://www.example.co.uk/images/1.jpg";
$handle = @fopen("$image", "r");
if(strpos($handle, "Resource id") !== false)
{
echo "file does exist";
}
else
{
echo "file does not exist";
}
?>

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The logic explained

Ok, so if the file exists (1.jpg) the fopen function will throw back a “resource id” response. So I check the response to see if “response id” exists with the strpos function. It’s really as simple as that.

I’m not entirely sure if my method is the best, nor the most efficient, but it seems to work pretty well, and I can’t think of any other methods. Anyone know of any other/better methods?

Better solution

Thanks to a comment left by Paul I’ve been made aware of a better solution.

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$url = "http://www.example.com/index.php";
$header_response = get_headers($url, 1);
if ( strpos( $header_response[0], "404" ) !== false )
{
  // FILE DOES NOT EXIST
} 
else 
{
  // FILE EXISTS!!
}

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