php 判断远路图片是否有效

	$url = "http://www.iteye.com/upload/logo/user/275746/46a4c886-427e-3554-b195-083430beb92a.jpg";
	echo "<a href='$url'>$url</a><br/>";
	$arr = get_headers($url,1);
	echo $arr["Content-Type"]; //image/jpeg

$url = 'http://www.example.com';

print_r(get_headers($url));

print_r(get_headers($url, 1));
?> 
上例的输出类似于：


Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Date: Sat, 29 May 2004 12:28:13 GMT
    [2] => Server: Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
    [4] => ETag: "3f80f-1b6-3e1cb03b"
    [5] => Accept-Ranges: bytes
    [6] => Content-Length: 438
    [7] => Connection: close
    [8] => Content-Type: text/html
)

Array
(
    [0] => HTTP/1.1 200 OK
    [Date] => Sat, 29 May 2004 12:28:14 GMT
    [Server] => Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [Last-Modified] => Wed, 08 Jan 2003 23:11:55 GMT
    [ETag] => "3f80f-1b6-3e1cb03b"
    [Accept-Ranges] => bytes
    [Content-Length] => 438
    [Connection] => close
    [Content-Type] => text/html
)