PHP checks whether remote files exist

Briefly explain the above code. Get_headers is used to access a remote address and return the HTTP header sent by the server as an array. $ Header [0] indicates the status code returned by the server (if no exception occurs, the status code should be the first one ). Make sure that a file is in.. SyntaxHighlighter. all ();

 

Briefly explain the above code. Get_headers is used to access a remote address and return the HTTP header sent by the server as an array. $ Header [0] indicates the status code returned by the server (if no exception occurs, the status code should be the first one ).

To determine whether a file exists on the remote server, you only need to confirm that the status code returned when accessing this file is "HTTP/1.1 200 OK" (of course, you can also determine that if the status code is Not "HTTP/1.1 404 Not Found ", file exists, but I always feel insecure. after all, there are other status codes such as 301,400 ).

Example of getting three HTTP response codes:

Function get_http_response_code ($ theURL ){

$ Headers = get_headers ($ theURL );

Return substr ($ headers [0], 9, 3 );

}

?>

Example of how to exclude redirection:

 

/**

* Fetches all the real headers sent by the server in response to a HTTP request without redirects

* Obtain a header that does not contain redirection.

*/

 

Function get_real_headers ($ url, $ format = 0, $ follow_redirect = 0 ){

If (! $ Follow_redirect ){

// Set new default options

$ Opts = array ('http' =>

Array ('max _ redirects' => 1, 'Ignore _ errors '=> 1)

);

Stream_context_get_default ($ opts );

}

// Get headers

$ Headers = get_headers ($ url, $ format );

// Restore default options

If (isset ($ opts )){

$ Opts = array ('http' =>

Array ('max _ redirects' => 20, 'Ignore _ errors '=> 0)

);

Stream_context_get_default ($ opts );

}

// Return

Return $ headers;

}

?>

 

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