PHP detects whether remote file exists

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

$hander_array = get_headers ( $url );

if ($header_array [0] == 'HTTP/1.1 200 OK') {

echo 'File exists';

} else {

echo 'File does not exist';

}

Briefly explain the above code. The function of get_headers is to access a remote address and return the HTTP headers sent by the server in the form of an array. And $header[0] is the status code returned by the server (if nothing else happens, the status code should be the first one returned).

To confirm that a file exists on the remote server, just make sure that the status code returned by accessing the file is "HTTP/1.1 200 OK" (of course you can also determine if the status code is not "HTTP/1.1 404 Not Found" ", the file exists, but it always feels unsafe. After all, there are other status codes such as 301, 400).

Example of obtaining three-digit HTTP response code:

<?php  
function get_http_response_code($theURL) {  
    $headers = get_headers($theURL);  
    return substr($headers[0], 9, 3);  
}  
?>

Example of excluding redirection:

<?php  
/** 
 * Fetches all the real headers sent by the server in response to a HTTP request without redirects 
 * 获取不包含重定向的报头 
 */  
   
function get_real_headers($url,$format=0,$follow_redirect=0) {  
  if (!$follow_redirect) {  
    //set new default options  
    $opts = array(&#39;http&#39; =>  
        array(&#39;max_redirects&#39;=>1,&#39;ignore_errors&#39;=>1)  
    );  
    stream_context_get_default($opts);  
  }  
  //get headers  
    $headers=get_headers($url,$format);  
    //restore default options  
  if (isset($opts)) {  
    $opts = array(&#39;http&#39; =>  
        array(&#39;max_redirects&#39;=>20,&#39;ignore_errors&#39;=>0)  
    );  
    stream_context_get_default($opts);  
  }  
  //return  
    return $headers;  
}  
?>