stream_get_contents() can be used instead of fread() even with local files.
(PHP 5, PHP 7, PHP 8)
stream_get_contents — 读取资源流到一个字符串
$handle
, int $maxlength = -1
, int $offset = -1
) : string|false
与 file_get_contents() 一样，但是
stream_get_contents() 是对一个已经打开的资源流进行操作，并将其内容写入一个字符串返回。
返回的内容取决于 maxlength 字节长度和 offset 指定的起始位置。
handle (resource)一个资源流（例如 fopen() 操作之后返回的结果）
maxlength (int)需要读取的最大的字节数。默认是-1（读取全部的缓冲数据）。
offset (int)在读取数据之前先查找指定的偏移量。如果这个数字是负数，就不进行查找，直接从当前位置开始读取。
返回一个字符串 或者在失败时返回 false.
Example #1 stream_get_contents() 例子
<?php
if ($stream = fopen('http://www.example.com', 'r')) {
// print all the page starting at the offset 10
echo stream_get_contents($stream, -1, 10);
fclose($stream);
}
if ($stream = fopen('http://www.example.net', 'r')) {
// print the first 5 bytes
echo stream_get_contents($stream, 5);
fclose($stream);
}
?>
Note: 此函数可安全用于二进制对象。
stream_get_contents() can be used instead of fread() even with local files.
/*
* problem: stream_get_contents blocks / is very slow.
* I have tried
* 1: stream_set_blocking, doesn't make a difference.
* 2: stream_get_meta_data['unread_bytes'] = ITS BUGGED, ALWAYS SAYS 0.
* 3: feof(): ALSO EFFING BLOCKING
* 4: my_stream_get_contents hack... kinda working! :D
*/
function my_stream_get_contents ($handle, $timeout_seconds = 0.5)
{
$ret = "";
// feof ALSO BLOCKS:
// while(!feof($handle)){$ret.=stream_get_contents($handle,1);}
while (true) {
$starttime = microtime(true);
$new = stream_get_contents($handle, 1);
$endtime = microtime(true);
if (is_string($new) && strlen($new) >= 1) {
$ret .= $new;
}
$time_used = $endtime - $starttime;
// var_dump('time_used:',$time_used);
if (($time_used >= $timeout_seconds) || ! is_string($new) ||
(is_string($new) && strlen($new) < 1)) {
break;
}
}
return $ret;
}
It is important to know that stream_get_contents behaves differently with different versions of PHP. Consider the following
<?php
$handle = fopen('file', 'w+'); // truncate + attempt to create
fwrite($handle, '12345'); // file position > 0
rewind($handle); // position = 0
$content = stream_get_contents($handle); // file position = 0 in PHP 5.1.6, file position > 0 in PHP 5.2.17!
fwrite($handle, '6789');
fclose($handle);
/**
*
* 'file' content
*
* PHP 5.1.6:
* 67895
*
* PHP 5.2.17:
* 123456789
*
*/
?>
As a result, stream_get_contents() affects file position in 5.1, and do not affect file position in 5.2 or better.
In that case when stream_get_contents/fread/fgets or other stream reading functions block indefinitely your script because they don't reached the limit of bytes to read use the socket_get_meta_data function to figure out the number of the bytes to read. It returns an array that contains a key named 'unread_bytes' and then pass that number to your favourite stream reading functions second parameter to read from the stream.
Maybe a good workaround to use the stream_select function, and set the socket to non-blocking mode with the use of stream_set_blocking($stream, 0). In this case the socket reading functions work properly.
Cheers, Ervin
When omitting the parameter $maxlength, any received bytes are stacked up until the underlying stream is not readable anymore, the the function returns that stack in one piece.