Php filters nonexistent image resource _ php instances

This article summarizes several methods for filtering non-existent image resources using php, which is very simple and practical. For more information, see. Method 1:

The simplest method is to use fopen () to check whether the file can be opened. If the file can be opened, the file exists.

<?php$url = 'http://www.php.net/images/test.jpg';if( @fopen( $url, 'r' ) ) {  echo 'File Exits';} else { echo 'File Do Not Exits';}?>

Method 2:

/*** Filter nonexistent image resources ** @ author wanggeng
 
  
* @ Return vodi */private static function _ checkAll ($ url) {$ curl = curl_init ($ url); curl_setopt ($ curl, CURLOPT_NOBODY, true); $ result = false; $ res = curl_exec ($ curl); if ($ res! = False) {$ statusCode = curl_getinfo ($ curl, CURLINFO_HTTP_CODE); if ($ statusCode = 200) {$ result = true ;}} curl_close ($ curl ); return $ result ;}
 

First, create a curl link to the executed url, that is, the image or file link.
The initial variable is false.
Or the header information of the link. Each http request has an http Code.
We will verify it based on this code.
If the returned code is 200, it indicates that the resource exists and the previous variable has a value of true. Otherwise, no value is assigned.

Method 3:

CURL Method

CURL is a very useful class library. Let's take a look at how to use it to determine.

<? Php $ url2 = 'HTTP: // www.php.net/test.jpg'commandid ch = curl_init (); $ timeout = 10; curl_setopt ($ ch, CURLOPT_URL, $ url2); curl_setopt ($ ch, CURLOPT_HEADER, 1); curl_setopt ($ ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt ($ ch, CURLOPT_CONNECTTIMEOUT, $ timeout); $ contents = curl_exec ($ ch); // echo $ contents; if (preg_match ("/404/", $ contents) {echo 'file does not exist ';}?>

After curl_exec () is executed, if the file does not exist, the following information is returned:

HTTP/1.1 404 Not FoundDate: Tue, 14 Feb 2012 05:08:34 GMTServer: ApacheAccept-Ranges: bytesContent-Length: 354Content-Type: text/html

Use regular expressions to check whether 404 exists. If yes, the file does not exist.

The above is all the content of this article. I hope you will like it.