php怎麼判斷遠端圖片是否存在

php判斷遠端圖片是否存在的方法：

function file_exists($url) {
$curl = curl_init($url);
// 不取回資料
curl_setopt($curl, CURLOPT_NOBODY, true);
// 傳送請求
$result = curl_exec($curl);
$found = false;
// 如果請求沒有傳送失敗
if ($result !== false) {
// 再檢查http響應碼是否為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 {$info['path']} HTTP/1.1rn");
    fputs($fp, "Host: {$info['host']}rn");
    fputs($fp, "Connection: closernrn");
    $headers = array();
    while(!feof($fp)) {
    $line = fgets($fp);
    if($line != "rn") {
    $headers[] = $line;
    }else {
    break;
    }
    }

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

通過http狀態碼來判斷檔案是否存在，比如，響應 302,301,404等都為不存在，如果是200，304，等可以視為檔案存在。

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 '檔案不存在';
    }
    ?>