Detailed explanation of PHP Streams stream

This article mainly introduces the detailed introduction and use of PHP Streams (stream). PHP Streams is a built-in core operation and may be rarely used by ordinary developers. It is used to unify file, network, data compression and other file-like operations, and provides a set of common function interfaces for these file-like operations. I hope to be helpful.

PHP Streams is a built-in core operation that may be rarely used by ordinary developers. It is used to unify file, network, data compression and other file-like operations, and provides a set of common functions for these file-like operations. interface.

A stream is a resource object with streaming behavior, and each stream object has a wrapper class. Stream can be referenced through ://. Among them, is the name of the packaging class, and the content in is specified by the syntax of the packaging class. The syntax of different packaging classes will be different.
Let’s take a look at the built-in packaging classes that PHP has by default:

print_r(stream_get_wrappers());
/*
Array
(
  [0] => php
  [1] => file
  [2] => glob
  [3] => data
  [4] => http
  [5] => ftp
  [6] => zip
  [7] => compress.zlib
  [8] => https
  [9] => ftps
  [10] => phar
)
*/

Look at the protocols supported by PHP in the PHP manual and packaging classes.
Look at the following code that uses file_get_contents() to obtain data:

/* Read local file from /home/bar */
 $localfile = file_get_contents ( "/home/bar/foo.txt" );
 
 /* Identical to above, explicitly naming FILE scheme */
 $localfile = file_get_contents ( "file:///home/bar/foo.txt" );
 
 /* Read remote file from www.example.com using HTTP */
 $httpfile  = file_get_contents ( "http://www.example.com/foo.txt" );
 
 /* Read remote file from www.example.com using HTTPS */
 $httpsfile = file_get_contents ( "https://www.example.com/foo.txt" );
 
 /* Read remote file from ftp.example.com using FTP */
 $ftpfile  = file_get_contents ( "ftp://user:pass@ftp.example.com/foo.txt" );
 
 /* Read remote file from ftp.example.com using FTPS */
 $ftpsfile  = file_get_contents ( "ftps://user:pass@ftp.example.com/foo.txt" );

Actually readfile('/path/to/ somefile.txt') or readfile('file:///path/to/somefile.txt'), these two methods are equivalent. Because PHP's default packaging class is file://.

The manual clearly states that you can register your own wrapper through stream_register_wrapper(). You can check out the examples in the manual.
OK, here is a brief introduction to PHP://, which is a wrapper class used by PHP to handle IO streams (click here to see an example). More powerful input and output streams can be accessed through PHP://:

php://stdin: access the corresponding input stream of the PHP process, such as used to obtain keyboard input when cli executes a script.
php://stdout: Access the corresponding output stream of the PHP process.
php://stderr: Access the corresponding error output of the PHP process.
php://input: A read-only stream that accesses the requested raw data.
php://output: Write-only data stream, written to the output area in the same way as print and echo.
php://fd: Allows direct access to the specified file descriptor. Example php://fd/3 refers to file descriptor 3.
php://memory: Allows reading and writing temporary data. Store data in memory.
php://temp: Same as above, it will be stored in a temporary file after the amount of memory reaches the predefined limit (default is 2MB).
php://filter: filter.

PHP can also modify and enhance packaging classes through context and filter.
(1) Regarding context, for example, PHP uses stream_context_create() to set the timeout for obtaining files. You must have used this code:

$opts = array(
  'http'=>array(
    'method'=>"GET",
    'timeout'=>60,
  )
);
$context = stream_context_create($opts);
$html =file_get_contents('http://www.jb51.net', false, $context);

(2) Regarding filter filters, first let’s take a look at what built-in filters PHP has:

print_r(stream_get_filters());
/*
Array
(
  [0] => convert.iconv.*
  [1] => mcrypt.*
  [2] => mdecrypt.*
  [3] => string.rot13
  [4] => string.toupper
  [5] => string.tolower
  [6] => string.strip_tags
  [7] => convert.*
  [8] => consumed
  [9] => dechunk
  [10] => zlib.*
)
*/

Custom filters can be created through stream_filter_register() and the built-in php_user_filter, as follows:

/* Define our filter class */
class strtoupper_filter extends php_user_filter {
  function filter ( $in , $out , & $consumed , $closing )
  {
    while ( $bucket = stream_bucket_make_writeable ( $in )) {
      $bucket -> data = strtoupper ( $bucket -> data );
      $consumed += $bucket -> datalen ;
      stream_bucket_append ( $out , $bucket );
    }
    return PSFS_PASS_ON ;
  }
}
 
/* Register our filter with PHP */
stream_filter_register ( "strtoupper" , "strtoupper_filter" )
or die( "Failed to register filter" );
 
$fp = fopen ( "foo-bar.txt" , "w" );
 
/* Attach the registered filter to the stream just opened */
stream_filter_append ( $fp , "strtoupper" );
 
fwrite ( $fp , "Line1\n" );
fwrite ( $fp , "Word - 2\n" );
fwrite ( $fp , "Easy As 123\n" );
 
fclose ( $fp );
 
 
readfile ( "foo-bar.txt" );
/*
结果如下：
LINE1
WORD - 2
EASY AS 123
*/

Provide the list of streams functions in PHP as follows:

stream_bucket_append函数：为队列添加数据　
stream_bucket_make_writeable函数：从操作的队列中返回一个数据对象
stream_bucket_new函数：为当前队列创建一个新的数据
stream_bucket_prepend函数：预备数据到队列　
stream_context_create函数：创建数据流上下文
stream_context_get_default函数：获取默认的数据流上下文
stream_context_get_options函数：获取数据流的设置
stream_context_set_option函数：对数据流、数据包或者上下文进行设置
stream_context_set_params函数：为数据流、数据包或者上下文设置参数
stream_copy_to_stream函数：在数据流之间进行复制操作
stream_filter_append函数：为数据流添加过滤器
stream_filter_prepend函数：为数据流预备添加过滤器
stream_filter_register函数：注册一个数据流的过滤器并作为PHP类执行
stream_filter_remove函数：从一个数据流中移除过滤器
stream_get_contents函数：读取数据流中的剩余数据到字符串
stream_get_filters函数：返回已经注册的数据流过滤器列表
stream_get_line函数：按照给定的定界符从数据流资源中获取行
stream_get_meta_data函数：从封装协议文件指针中获取报头/元数据
stream_get_transports函数：返回注册的Socket传输列表
stream_get_wrappers函数：返回注册的数据流列表
stream_register_wrapper函数：注册一个用PHP类实现的URL封装协议
stream_select函数：接收数据流数组并等待它们状态的改变
stream_set_blocking函数：将一个数据流设置为堵塞或者非堵塞状态
stream_set_timeout函数：对数据流进行超时设置
stream_set_write_buffer函数：为数据流设置缓冲区
stream_socket_accept函数：接受由函数stream_ socket_server()创建的Socket连接
stream_socket_client函数：打开网络或者UNIX主机的Socket连接
stream_socket_enable_crypto函数：为一个已经连接的Socket打开或者关闭数据加密
stream_socket_get_name函数：获取本地或者网络Socket的名称
stream_socket_pair函数：创建两个无区别的Socket数据流连接
stream_socket_recvfrom函数：从Socket获取数据，不管其连接与否
stream_socket_sendto函数：向Socket发送数据，不管其连接与否
stream_socket_server函数：创建一个网络或者UNIX Socket服务端
stream_wrapper_restore函数：恢复一个事先注销的数据包
stream_wrapper_unregister函数：注销一个URL地址包

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