PHP检测远端资料是否存在

<?php
$url = 'http://example.com';
$hander_array = get_headers ( $url );
if ($header_array [0] == 'HTTP/1.1 200 OK') {
	echo '文件存在';
} else {
	echo '文件不存在';
} 

<?php
function get_http_response_code($theURL) {
    $headers = get_headers($theURL);
    return substr($headers[0], 9, 3);
}
?> 

<?php
/**
 * Fetches all the real headers sent by the server in response to a HTTP request without redirects
 * 获取不包含重定向的报头
 */
 
function get_real_headers($url,$format=0,$follow_redirect=0) {
  if (!$follow_redirect) {
    //set new default options
    $opts = array('http' =>
        array('max_redirects'=>1,'ignore_errors'=>1)
    );
    stream_context_get_default($opts);
  }
  //get headers
    $headers=get_headers($url,$format);
    //restore default options
  if (isset($opts)) {
    $opts = array('http' =>
        array('max_redirects'=>20,'ignore_errors'=>0)
    );
    stream_context_get_default($opts);
  }
  //return
    return $headers;
}
?>