php怎么判断远程图片是否存在

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://HdhCmsTestbaidu测试数据/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://HdhCmsTesttest测试数据/images/test.jpg';

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

CURL方法:

<?php
    $url2 = 'http://HdhCmsTesttest测试数据/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';
    }
    ?>