stream_get_contents()

(PHP 5, PHP 7)

读取资源流到一个字符串

说明

stream_get_contents(resource $handle[,int $maxlength=-1[,int $offset=-1]]): string

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。

参数

$handle(resource): 一个资源流（例如fopen()操作之后返回的结果）
$maxlength(integer): 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(integer): 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。

返回值

返回一个字符串或者在失败时返回FALSE.

更新日志

版本	说明
5.1.0	增加参数`$offset`。

范例

Example #1stream_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);
}
?>

注释

Note:此函数可安全用于二进制对象。

参见

fgets() 从文件指针中读取一行
fread() 读取文件（可安全用于二进制文件）
fpassthru() 输出文件指针处的所有剩余数据

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.

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 seems that using fiddler as a proxy in the stream context options causes this function to throw a warning:
Warning: stream_get_contents() [function.stream-get-contents]: SSL: An existing connection was forcibly closed by the remote host.

some times this functions cause an max execution time time error, Why?
Simple, if you use it the function wait for have the specified byte length into the resource or the end of file, but, several times this not happend, so we need implement an artificial flag like this:
$tmp = stream_get_contents($this->socket, 42);
while($tmp[42] != 'N'){
//Your code...
$tmp = stream_get_contents($this->socket, 42);
}