The streamWrapper class

(PHP 4 >= 4.3.2, PHP 5, PHP 7)

简介

Allows you to implement your own protocol handlers and streams for use with all the other filesystem functions (such as fopen(), fread() etc.).

Note:

This is NOT a real class, only a prototype of how a class defining its own protocol should be.

Note:

Implementing the methods in other ways than described here can lead to undefined behaviour.

An instance of this class is initialized as soon as a stream function tries to access the protocol it is associated with.

类摘要

streamWrapper {
/* 属性 */
public resource $context ;
/* 方法 */
__construct ( void )
__destruct ( void )
public dir_closedir ( void ) : bool
public dir_opendir ( string $path , int $options ) : bool
public dir_readdir ( void ) : string
public dir_rewinddir ( void ) : bool
public mkdir ( string $path , int $mode , int $options ) : bool
public rename ( string $path_from , string $path_to ) : bool
public rmdir ( string $path , int $options ) : bool
public stream_cast ( int $cast_as ) : resource
public stream_close ( void ) : void
public stream_eof ( void ) : bool
public stream_flush ( void ) : bool
public stream_lock ( int $operation ) : bool
public stream_metadata ( string $path , int $option , mixed $value ) : bool
public stream_open ( string $path , string $mode , int $options , string &$opened_path ) : bool
public stream_read ( int $count ) : string
public stream_seek ( int $offset , int $whence = SEEK_SET ) : bool
public stream_set_option ( int $option , int $arg1 , int $arg2 ) : bool
public stream_stat ( void ) : array
public stream_tell ( void ) : int
public stream_truncate ( int $new_size ) : bool
public stream_write ( string $data ) : int
public unlink ( string $path ) : bool
public url_stat ( string $path , int $flags ) : array
}

属性

resource context

The current context, or NULL if no context was passed to the caller function.

Use the stream_context_get_options() to parse the context.

Note:

This property must be public so PHP can populate it with the actual context resource.

参见

Table of Contents

User Contributed Notes

Anonymous 21-Sep-2011 12:02
Here is a very simple stream wrapper which calls your callback function for reads:

<?php

class CallbackUrl
{
    const WRAPPER_NAME = 'callback';

    public $context;
    private $_cb;
    private $_eof = false;

    private static $_isRegistered = false;

    public static function getContext($cb)
    {
        if (!self::$_isRegistered) {
            stream_wrapper_register(self::WRAPPER_NAME, get_class());
            self::$_isRegistered = true;
        }
        if (!is_callable($cb)) return false;
        return stream_context_create(array(self::WRAPPER_NAME => array('cb' => $cb)));
    }

    public function stream_open($path, $mode, $options, &$opened_path)
    {
        if (!preg_match('/^r[bt]?$/', $mode) || !$this->context) return false;
        $opt = stream_context_get_options($this->context);
        if (!is_array($opt[self::WRAPPER_NAME]) ||
            !isset($opt[self::WRAPPER_NAME]['cb']) ||
            !is_callable($opt[self::WRAPPER_NAME]['cb'])) return false;
        $this->_cb = $opt[self::WRAPPER_NAME]['cb'];
        return true;
    }

    public function stream_read($count)
    {
        if ($this->_eof || !$count) return '';
        if (($s = call_user_func($this->_cb, $count)) == '') $this->_eof = true;
        return $s;
    }

    public function stream_eof()
    {
        return $this->_eof;
    }
}

class Test {
    private $_s;
    public function __construct($s)
    {
        $this->_s = $s;
    }
    public function read($count) {
        return fread($this->_s, $count);
    }
}

$t = new Test(fopen('/etc/services', 'r'));
$fd = fopen('callback://', 'r', false, CallbackUrl::getContext(array($t, 'read')));
while(($buf = fread($fd, 128)) != '') {
    print $buf;
}
?>
isaac dot z dot no dot foster at spam dot gmail dot please dot com 22-Oct-2010 09:12
It's worth noting that the interface defined by yannick at gmail should not always be implemented by a stream wrapper class, as several of the methods should not be implemented if the class has no use for them (as per the manual).

Specifically, mkdir, rename, rmdir, and unlink are methods that "should not be defined" if the wrapper has no use for them. The consequence is that the appropriate error message will not be returned.

If the interface is implemented, you won't have the flexibility to not implement those methods.

Not trying to be academic, but it was useful for me.
yannick dot battail at gmail dot com 17-Jul-2009 02:38
a php interface for wrapper

<?php
interface WrapperInterface
{
    /**
     * resource context
     *
     * @var resource
     */
    //public $context;

    /**
     * constructor
     *
     */
    public function __construct();

    /**
     *
     *
     * @return bool
     */
    public function dir_closedir();

    /**
     * Enter description here...
     *
     * @param string $path
     * @param int $options
     * @return bool
     */
    public function dir_opendir($path , $options);

    /**
     * Enter description here...
     *
     * @return string
     */
    public function dir_readdir();

    /**
     * Enter description here...
     *
     * @return bool
     */
    public function dir_rewinddir();

    /**
     * Enter description here...
     *
     * @param string $path
     * @param int $mode
     * @param int $options
     * @return bool
     */
    public function mkdir($path , $mode , $options);

    /**
     * Enter description here...
     *
     * @param string $path_from
     * @param string $path_to
     * @return bool
     */
    public function rename($path_from , $path_to);

    /**
     * Enter description here...
     *
     * @param string $path
     * @param int $options
     * @return bool
     */
    public function rmdir($path , $options);

    /**
     * Enter description here...
     *
     * @param int $cast_as
     * @return resource
     */
    public function stream_cast($cast_as);

    /**
     * Enter description here...
     *
     */
    public function stream_close();

    /**
     * Enter description here...
     *
     * @return bool
     */
    public function stream_eof();

    /**
     * Enter description here...
     *
     * @return bool
     */
    public function stream_flush();

    /**
     * Enter description here...
     *
     * @param mode $operation
     * @return bool
     */
    public function stream_lock($operation);

    /**
     * Enter description here...
     *
     * @param string $path
     * @param string $mode
     * @param int $options
     * @param string &$opened_path
     * @return bool
     */
    public function stream_open($path , $mode , $options , &$opened_path);

    /**
     * Enter description here...
     *
     * @param int $count
     * @return string
     */
    public function stream_read($count);

    /**
     * Enter description here...
     *
     * @param int $offset
     * @param int $whence = SEEK_SET
     * @return bool
     */
    public function stream_seek($offset , $whence = SEEK_SET);

    /**
     * Enter description here...
     *
     * @param int $option
     * @param int $arg1
     * @param int $arg2
     * @return bool
     */
    public function stream_set_option($option , $arg1 , $arg2);

    /**
     * Enter description here...
     *
     * @return array
     */
    public function stream_stat();

    /**
     * Enter description here...
     *
     * @return int
     */
    public function stream_tell();

    /**
     * Enter description here...
     *
     * @param string $data
     * @return int
     */
    public function stream_write($data);

    /**
     * Enter description here...
     *
     * @param string $path
     * @return bool
     */
    public function unlink($path);

    /**
     * Enter description here...
     *
     * @param string $path
     * @param int $flags
     * @return array
     */
    public function url_stat($path , $flags);
}

?>