stream_get_meta_data()
(PHP 4 >= 4.3.0, PHP 5, PHP 7)
从封装协议文件指针中取得报头/元数据
说明
stream_get_meta_data(int $fp): array
返回现有$stream的信息。可以是任何通过fopen(),fsockopen()和pfsockopen()建立的流。返回的数组包含以下项目:
$timed_out(bool)-如果在上次调用fread()或者fgets()中等待数据时流超时了则为
TRUE
。$blocked(bool)-如果流处于阻塞 IO 模式时为
TRUE
。参见stream_set_blocking()。$eof(bool)-如果流到达文件末尾时为
TRUE
。注意对于 socket 流甚至当$unread_bytes为非零值时也可以为TRUE
。要测定是否有更多数据可读,用feof()替代读取本项目的值。$unread_bytes(int)-当前在 PHP 自己的内部缓冲区中的字节数。
Note:不要在脚本中使用此值。
以下项目是 PHP 4.3 新加的:
$stream_type(string)-一个描述流底层实现的标注。
$wrapper_type(string)-一个描述流的分层协议封装实现的标注。更多关于封装协议的信息见支持的协议和封装协议。
$wrapper_data(mixed)-当前流附加的封装协议数据。更多封装协议及其数据的信息见支持的协议和封装协议。
$filters(array)-包含有被叠加在当前流的任何过滤器名的数组。过滤器的文档见附录中的可用过滤器列表。
Note:
本函数是 PHP 4.3 引进的,在此版本之前,可以用socket_get_status()来取得前四个项目并且仅能用于基于 socket 的流。
在 PHP 4.3 及以后版本中,socket_get_status()是本函数的别名。
Note:本函数不能作用于通过Socket 扩展库创建的流。
以下项目为 PHP 5.0 新加:
$mode(string)-对当前流所要求的访问类型(见fopen()中的表格 1)。
$seekable(bool)-是否可以在当前流中定位。
$uri(string)-与当前流关联的 URI 或文件名。
In PHP 5.4.24 and 5.4.25, this command does not correctly return the stream blocking status. It always returns ['blocked'] == 1 regardless of the actual blocking mode. A call to stream_set_blocking($stream, 0) will succeed (return TRUE) and subsequent calls to stream_get_contents($stream) will NOT block, even though a call to stream_get_meta_data($stream) will return 'blocked' == 1. Hopefully this will save some people a bunch of debugging time. See bug report #47918 for more information (http://bugs.php.net/bug.php?id=47918). Proof: <?php $d = array( 0 => array('pipe', 'r'), 1 => array('pipe', 'w'), 2 => array('file', 'error.log', 'a') ); $p = proc_open('php -S localhost:8000', $d, $pipes); if (!is_resource($p)) die("proc_open() failed\n"); // Set child's stdout pipe to non-blocking. if (!stream_set_blocking($pipes[1], 0)) { die("stream_set_blocking() failed\n"); } else { echo "Non-blocking mode should be set.\n"; } // View the status of that same pipe. // Note that 'blocked' is 1! This appears to be wrong. print_r(stream_get_meta_data($pipes[1])); // Try to read something. This will block if in blocking mode. // If it does not block, stream_set_blocking() worked but // stream_get_meta_data() is lying about blocking mode. $data = stream_get_contents($pipes[1]); echo "data = '$data'\n"; ?> Output: Non-blocking mode should be set. Array ( [stream_type] => STDIO [mode] => r [unread_bytes] => 0 [seekable] => [timed_out] => [blocked] => 1 // << claims to be in blocking mode [eof] => ) data = '' // this would never appear if we blocked.
Below is a function I wrote to pull the "Last-Modified" header from a given URL. In PHP version 4.3 and above, it takes advantage of the stream_get_meta_data function, and in older version it uses a conventional GET procedure. On failure to connect to $url, it returns NULL. If the server does not return the Last-Modified header, it returns the current time. All times are returned in PHP's integer format (seconds since epoch). Use it as so: $last_modified = stream_last_modified('http://www.php.net/news.rss'); if (!is_null($last_modified)) if ($last_modified < time() 3600) //Older than an hour echo 'URL is older than an hour.'; else echo 'URL is fairly new.'; else echo 'Invalid URL!'; function stream_last_modified($url) { if (function_exists('version_compare') && version_compare(phpversion(), '4.3.0') > 0) { if (!($fp = @fopen($url, 'r'))) return NULL; $meta = stream_get_meta_data($fp); for ($j = 0; isset($meta['wrapper_data'][$j]); $j++) { if (strstr(strtolower($meta['wrapper_data'][$j]), 'last-modified')) { $modtime = substr($meta['wrapper_data'][$j], 15); break; } } fclose($fp); } else { $parts = parse_url($url); $host = $parts['host']; $path = $parts['path']; if (!($fp = @fsockopen($host, 80))) return NULL; $req = "HEAD $path HTTP/1.0\r\nUser-Agent: PHP/".phpversion()."\r\nHost: $host:80\r\nAccept: */*\r\n\r\n"; fputs($fp, $req); while (!feof($fp)) { $str = fgets($fp, 4096); if (strstr(strtolower($str), 'last-modified')) { $modtime = substr($str, 15); break; } } fclose($fp); } return isset($modtime) ? strtotime($modtime) : time(); }
here is just an example how to read out all meta data. how ever I found out that the "seekable"-entry doesn't exist in most of the streaming media files. if (!($fp = @fopen($url, 'r'))) return NULL; $meta = stream_get_meta_data($fp); foreach(array_keys($meta) as $h){ $v = $meta[$h]; echo "".$h.": ".$v."<br/>"; if(is_array($v)){ foreach(array_keys($v) as $hh){ $vv = $v[$hh]; echo "_".$hh.": ".$vv."<br/>"; } } } fclose($fp);
Apparently, custom wrappers are always seekable.