PHPget_headers function to determine whether a remote file exists _ PHP Tutorial

The PHPget_headers function checks whether a remote file exists. I used to talk about articles about how to determine whether a remote file exists in php, where I used the fopen, sockt, and curl functions to check whether the remote file exists, next I will introduce the article about how to use php to determine whether a remote file exists. I will introduce how to use the fopen, sockt, and curl functions to check whether a remote file exists, next I will introduce how to use get_headers to check whether the remote file exists. For more information, see.

First, let's take a look at the get_headers () function.

Get_headers () returns an array containing the header sent by the server to respond to an HTTP request.

Get_headers: Send the server response HTTP request
Get_headers (string url [link format])
Get_headers () returns the HTTP request of the server as an array. If the execution fails, FALSE and an error level E_WARNING are returned.

The optional parameter is set to 1. get_headers () can analyze the system response speed and the keys in the array.

Note: To use this function, you must use allow_url_fopen = On in php. ini.

Example

The code is as follows:

$ Url = 'http: // www.example.com '; Print_r (get_headers ($ url )); Print_r (get_headers ($ url, 1 )); ?> Return value Array ( [0] => HTTP/1.1 200 OK [1] => Date: Sat, 29 May 2004 12:28:13 GMT [2] => Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT [4] => ETag: "3f80f-1b6-3e1cb03b" [5] => Accept-Ranges: bytes [6] => Content-Length: 438 [7] => Connection: close [8] => Content-Type: text/html ) Array ( [0] => HTTP/1.1 200 OK [Date] => Sat, 29 May 2004 12:28:14 GMT [Server] => Apache/1.3.27 (Unix) (Red-Hat/Linux) [Last-Modified] => Wed, 08 Jan 2003 23:11:55 GMT [ETag] => "3f80f-1b6-3e1cb03b" [Accept-Ranges] => bytes [Content-Length] = & gt; 438 [Connection] => close [Content-Type] => text/html )

Example

The code is as follows:

// Determine whether a remote file exists Function remote_file_exists ($ url ){ $ ExecuteTime = ini_get ('max _ execution_time '); Ini_set ('max _ execution_time ', 0 ); $ Headers = @ get_headers ($ url ); Ini_set ('max _ execution_time ', $ executeTime ); If ($ headers ){ $ Head = explode ('', $ headers [0]); If (! Emptyempty ($ head [1]) & intval ($ head [1]) <400) return true; } Return false; }

Example 2

Example of how to exclude redirection:

The code is as follows:

/** * 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; }

...