PHP filters non-existent image resources, _PHP tutorial-PHP Tutorial-php.cn

PHP filters non-existent image resources, _PHP tutorial

WBOY

Release： 2016-07-13 09:55:35

Original

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php filters non-existent image resources,

Method 1:

The easiest way is to use fopen() to see if the file can be opened. If it can be opened, the file will of course exist.

<&#63;php
$url = 'http://www.bkjia.com/images/test.jpg';

if( @fopen( $url, 'r' ) ) 
{ 
 echo 'File Exits';
} 
else 
{
 echo 'File Do Not Exits';
}
&#63;>

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Method 2:

/** 
   * 筛选不存在的图片资源 
   * 
   * @author wanggeng <wanggeng123@vip.qq.com> 
   * @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; 
  }

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First create a curl link to the executed url, which is a link to the image or file
Initialize a variable to false
Or open the header information of the link. Each http request will have an http Code
We will verify based on this code
If the return code is 200, it proves that the resource exists. Give the previous variable a true value, otherwise no value will be assigned

Method three:

CURL method

CURL is a very useful class library. Let’s see how to use it to judge.

<&#63;php
$url2 = 'http://www.bkjia.com/test.jpg';

$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 '文件不存在';
}
&#63;>

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If the file does not exist after curl_exec() is executed, the following information will be returned:

HTTP/1.1 404 Not Found
Date: Tue, 14 Feb 2012 05:08:34 GMT
Server: Apache
Accept-Ranges: bytes
Content-Length: 354
Content-Type: text/html

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Use regular expressions to see if there is a 404. If so, the file does not exist.

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