php判断远程图片是否存在的方法：

function file_exists($url) {
$curl = curl_init($url);
// 不取回数据
curl_setopt($curl, CURLOPT_NOBODY, true);
// 发送请求
$result = curl_exec($curl);
$found = false;
// 如果请求没有发送失败
if ($result !== false) {
// 再检查http响应码是否为200
}

fsockopen版:

 $url = "http://www.baidu.com/img/baidu_sylogo1.gif";

 $info = parse_url($url);
 $fp = fsockopen($info['host'], 80,$errno, $errstr, 30);
 fputs($fp,"GET {$info['path']} HTTP/1.1\r\n");
 fputs($fp, "Host: {$info['host']}\r\n");
 fputs($fp, "Connection: close\r\n\r\n");
 $headers = array();
 while(!feof($fp)) {
 $line = fgets($fp);
 if($line != "\r\n") {
 $headers[] = $line;
 }else {
 break;
 }
 }

 echo "<pre>";
 print_r($headers);

通过http状态码来判断文件是否存在，比如，响应 302,301,404等都为不存在，如果是200，304，等可以视为文件存在。

fopen()方法:

<?php
 $url = 'http://www.test.com/images/test.jpg';

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

CURL方法:

<?php
 $url2 = 'http://www.test.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';
 }
 ?>

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