PHP uses the Get_headers function to determine whether a remote file exists _php tips

This example describes the way PHP uses the Get_headers function to determine whether a remote file exists. Share to everyone for your reference. The implementation methods are as follows:

Before speaking about the process of PHP to determine whether the existence of remote files are the use of Fopen,sockt,curl function to check the existence of remote files, the following I introduce the use of get_headers to check whether the remote file exists, interested friends can refer to.

First to understand the get_headers () function

Get_headers () returns an array of m containing headers that are sent by the server in response to an HTTP request.

Get_headers: The sending server responds to HTTP requests

Get_headers (string url[link format])

Get_headers () returns the server HTTP request m as an array if execution fails, it returns false and an incorrect horizontal e_warning.

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

Note: Using this function you need to put the Allow_url_fopen = on in the php.ini to use

The instance code is as follows:

Copy Code code as follows:

<?php
$url = ' http://www.jb51.net ';
Print_r (Get_headers ($url));
Print_r (Get_headers ($url, 1));
?>

The results of the operation are as follows:

Copy Code code as follows:

Array
(
[0] => http/1.1 OK
[1] => cache-control:max-age=1800
[2] => content-length:54874
[3] => content-type:text/html
[4] => content-location:http://www.jb51.net/index.htm
[5] => Last-modified:fri, Nov 2014 03:34:56 GMT
[6] => Accept-ranges:bytes
[7] => ETag: "B66ba847bcad01:bc5"
[8] => server:microsoft-iis/6.0
[9] => Date:fri, Nov 2014 03:37:34 GMT
[Ten] => Connection:close
)
Array
(
[0] => http/1.1 OK
[Cache-control] => max-age=1800
[Content-length] => 54874
[Content-type] => text/html
[Content-location] => http://www.jb51.net/index.htm
[Last-modified] => Fri, Nov 2014 03:34:56 GMT
[Accept-ranges] => bytes
[ETag] => "B66ba847bcad01:bc5"
[Server] => microsoft-iis/6.0
[Date] => Fri Nov 2014 03:37:35 GMT
[Connection] => Close
)

Determine if the remote file exists code as follows:

Copy Code code as follows:

To 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]) <) return true;
}
return false;
}

The instance code for excluding redirects is as follows:

Copy Code code as follows:

<?php
/**
* Fetches all of the real headers sent from the server in response to a HTTP request without redirects
* Get headers that do not contain redirects
*/

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;
}
?>

I hope this article will help you with your PHP program design.