“中国要复兴、富强，必须在开源软件领域起到主导作用，为了国家安全和人类发展，责无旁贷，我们须为此而奋斗”——By:云客
在开始这个主题前我们做一个实验，在你的drupal模块控制器中加一行代码：
file_put_contents("public://yunke.txt","Streams test");
然后访问这个控制器，看看发生了什么？没错页面上不会有什么改变，但也没有报告什么错误，那这行代码到底干了什么？
作为开发者你应该很熟悉file_put_contents（）这个函数，代码意思是将"Streams test"这个字符串写入一个文件中，
可是文件名却是："public://yunke.txt",它是什么意思？文件保存了吗？保存到哪里去了？
这就是本主题要讲的内容！
不知道"public://yunke.txt",很正常，但你可能知道php://input，没错，就是那个php读取原始post输入的东西
在微信公众账号管理系统中就是用这个来读取收到的原始XML数据，其实public://yunke.txt和php://input差不多，它们源自同一个概念
就是php流及流包装器，由于在一般的开发中很少用到它，所以很多开发者并不熟悉，但它功能强大，是php这门语言的一个重点内容
在java中也有类似概念，如果你对C语言熟悉，那么会倍感熟悉，它或多或少基于ANSI C 标准IO函数簇。
由于php流这个知识点属于php学习的范畴，并不限于drupal源码分析，所以我单独写了篇博客来介绍它：
请看：http://www.indrupal.com/node/174
那是本文的一部分，如果你对流不熟悉请务必暂停去阅读学习后再继续，否则你很难理解后面的内容，在文末附加一个流包装器的例子。
这里开始假定你已经学习完了流相关的知识，来看一看它在drupal中的运用：
还是从file_put_contents("public://yunke.txt","Streams test");说起
它是在公共文件目录里面建立一个叫做yunke.txt的文件，里面保存了字符串"Streams test"，那么这个公共文件目录在哪里？
它可以在站点配置文件中指定，如果你没有指定，那么默认是\sites\default\files，如果你按上面的方法做了，看一看是不是有这个文件？
drupal使用流这个概念来储存公有及私有文件并提供操作上的方便，私有文件可以保存到一个web访客无法通过url访问到的地方，这样就比较安全了
如何在settings.php文件中配置公有及私有文件的主目录：
$settings['file_public_path'] = "./yunke"; //所有公共文件都将保存到站点根目录的yunke文件夹下，若无默认是\sites\default\files
$settings['file_private_path'] = “/home/yunke”; //设置后需要做权限设定，以防止web访客通过url访问到文件，配置中若有此项就会在容器中注册私有流包装器
关于流方面的源码储存在：\core\lib\Drupal\Core\StreamWrapper里面
定义了一个php级别的流包装器接口：PhpStreamWrapperInterface
drupal用的包装器接口（继承自上面的接口）：StreamWrapperInterface
LocalStream：抽象的本地流包装器
额外定义了公共流包装器、私有流包装器、临时流包装器、只读流
这些包装器用一个包装器管理器来管理：
StreamWrapperManager：实现了StreamWrapperManagerInterface接口，主要作用是注册流包装器
调用流包装器管理器的代码位于drupal核心：Drupal\Core\DrupalKernel的preHandle方法中，有以下代码：
// Register stream wrappers.
$this->container->get('stream_wrapper_manager')->register();
而preHandle方法的调用是在多层HttpKernel核心处理中的预处理层：
http_middleware.kernel_pre_handle（Drupal\Core\StackMiddleware\KernelPreHandle）
请看本系列前面的《HttpKernel堆栈》一文
以上就是本主题的全部了，下面提供一个流包装器案例，是我从drupal中抽取出来，做了修改，可以独立使用的一个类，可以研究下它的实现：
class yunkeWrapper
{
public $context;
public $handle = null;
public $uri = null;
protected static $dir = "";
//public $dir = "dir";//可以是相对路径或绝对路径，空表示当前路径
public function dir_closedir()
{
closedir($this->handle);
// We do not really have a way to signal a failure as closedir() does not
// have a return value.
return true;
}
/**
* @return bool
*/
public function dir_opendir($uri, $options)
{
$this->uri = $uri;
$this->handle = opendir($this->getLocalPath());
return (bool)$this->handle;
}
/**
* @return string
*/
public function dir_readdir()
{
return readdir($this->handle);
}
/**
* @return bool
*/
public function dir_rewinddir()
{
rewinddir($this->handle);
// We do not really have a way to signal a failure as rewinddir() does not
// have a return value and there is no way to read a directory handler
// without advancing to the next file.
return true;
}
/**
* @return bool
*/
public function mkdir($uri, $mode, $options)
{
$this->uri = $uri;
$recursive = (bool)($options & STREAM_MKDIR_RECURSIVE);
if ($recursive) {
// $this->getLocalPath() fails if $uri has multiple levels of directories
// that do not yet exist.
$localpath = $this->getDirectoryPath() . '/' . $this->getTarget($uri);
} else {
$localpath = $this->getLocalPath($uri);
}
if ($options & STREAM_REPORT_ERRORS) {
return mkdir($localpath, $mode, $recursive);
} else {
return @mkdir($localpath, $mode, $recursive);
}
}
/**
* @return bool
*/
public function rename($from_uri, $to_uri)
{
return rename($this->getLocalPath($from_uri), $this->getLocalPath($to_uri));
}
/**
* @return bool
*/
public function rmdir($uri, $options)
{
$this->uri = $uri;
if ($options & STREAM_REPORT_ERRORS) {
return rmdir($this->getLocalPath());
} else {
return @rmdir($this->getLocalPath());
}
}
/**
* Retrieve the underlying stream resource.
*
* This method is called in response to stream_select().
*
* @param int $cast_as
* Can be STREAM_CAST_FOR_SELECT when stream_select() is calling
* stream_cast() or STREAM_CAST_AS_STREAM when stream_cast() is called for
* other uses.
*
* @return resource|false
* The underlying stream resource or FALSE if stream_select() is not
* supported.
*
* @see stream_select()
* @see http://php.net/manual/streamwrapper.stream-cast.php
*/
public function stream_cast($cast_as)
{
return $this->handle ? $this->handle : false;
}
/**
* Closes stream.
*/
public function stream_close()
{
return fclose($this->handle);
}
/**
* @return bool
*/
public function stream_eof()
{
return feof($this->handle);
}
/**
* @return bool
*/
public function stream_flush()
{
return fflush($this->handle);
}
/**
* @return bool
*/
public function stream_lock($operation)
{
if (in_array($operation, array(
LOCK_SH,
LOCK_EX,
LOCK_UN,
LOCK_NB))) {
return flock($this->handle, $operation);
}
return true;
}
/**
* Sets metadata on the stream.
*
* @param string $path
* A string containing the URI to the file to set metadata on.
* @param int $option
* One of:
* - STREAM_META_TOUCH: The method was called in response to touch().
* - STREAM_META_OWNER_NAME: The method was called in response to chown()
* with string parameter.
* - STREAM_META_OWNER: The method was called in response to chown().
* - STREAM_META_GROUP_NAME: The method was called in response to chgrp().
* - STREAM_META_GROUP: The method was called in response to chgrp().
* - STREAM_META_ACCESS: The method was called in response to chmod().
* @param mixed $value
* If option is:
* - STREAM_META_TOUCH: Array consisting of two arguments of the touch()
* function.
* - STREAM_META_OWNER_NAME or STREAM_META_GROUP_NAME: The name of the owner
* user/group as string.
* - STREAM_META_OWNER or STREAM_META_GROUP: The value of the owner
* user/group as integer.
* - STREAM_META_ACCESS: The argument of the chmod() as integer.
*
* @return bool
* Returns TRUE on success or FALSE on failure. If $option is not
* implemented, FALSE should be returned.
*
* @see http://php.net/manual/streamwrapper.stream-metadata.php
*/
public function stream_metadata($uri, $option, $value)
{
$target = $this->getLocalPath($uri);
$return = false;
switch ($option) {
case STREAM_META_TOUCH:
if (!empty($value)) {
$return = touch($target, $value[0], $value[1]);
} else {
$return = touch($target);
}
break;
case STREAM_META_OWNER_NAME:
case STREAM_META_OWNER:
$return = chown($target, $value);
break;
case STREAM_META_GROUP_NAME:
case STREAM_META_GROUP:
$return = chgrp($target, $value);
break;
case STREAM_META_ACCESS:
$return = chmod($target, $value);
break;
}
if ($return) {
// For convenience clear the file status cache of the underlying file,
// since metadata operations are often followed by file status checks.
clearstatcache(true, $target);
}
return $return;
}
/**
* @return bool
*/
public function stream_open($uri, $mode, $options, &$opened_path)
{
$this->uri = $uri;
$path = $this->getLocalPath();
$this->handle = ($options & STREAM_REPORT_ERRORS) ? fopen($path, $mode) : @
fopen($path, $mode);
if ((bool)$this->handle && $options & STREAM_USE_PATH) {
$opened_path = $path;
}
return (bool)$this->handle;
}
/**
* @return string
*/
public function stream_read($count)
{
return fread($this->handle, $count);
}
/**
* Seeks to specific location in a stream.
*
* This method is called in response to fseek().
*
* The read/write position of the stream should be updated according to the
* offset and whence.
*
* @param int $offset
* The byte offset to seek to.
* @param int $whence
* Possible values:
* - SEEK_SET: Set position equal to offset bytes.
* - SEEK_CUR: Set position to current location plus offset.
* - SEEK_END: Set position to end-of-file plus offset.
* Defaults to SEEK_SET.
*
* @return bool
* TRUE if the position was updated, FALSE otherwise.
*
* @see http://php.net/manual/streamwrapper.stream-seek.php
*/
public function stream_seek($offset, $whence = SEEK_SET)
{
// fseek returns 0 on success and -1 on a failure.
// stream_seek 1 on success and 0 on a failure.
return !fseek($this->handle, $offset, $whence);
}
/**
* Change stream options.
*
* This method is called to set options on the stream.
*
* @param int $option
* One of:
* - STREAM_OPTION_BLOCKING: The method was called in response to
* stream_set_blocking().
* - STREAM_OPTION_READ_TIMEOUT: The method was called in response to
* stream_set_timeout().
* - STREAM_OPTION_WRITE_BUFFER: The method was called in response to
* stream_set_write_buffer().
* @param int $arg1
* If option is:
* - STREAM_OPTION_BLOCKING: The requested blocking mode:
* - 1 means blocking.
* - 0 means not blocking.
* - STREAM_OPTION_READ_TIMEOUT: The timeout in seconds.
* - STREAM_OPTION_WRITE_BUFFER: The buffer mode, STREAM_BUFFER_NONE or
* STREAM_BUFFER_FULL.
* @param int $arg2
* If option is:
* - STREAM_OPTION_BLOCKING: This option is not set.
* - STREAM_OPTION_READ_TIMEOUT: The timeout in microseconds.
* - STREAM_OPTION_WRITE_BUFFER: The requested buffer size.
*
* @return bool
* TRUE on success, FALSE otherwise. If $option is not implemented, FALSE
* should be returned.
*/
public function stream_set_option($option, $arg1, $arg2)
{
trigger_error('stream_set_option() not supported for local file based stream wrappers',
E_USER_WARNING);
return false;
}
/**
* @return array
*/
public function stream_stat()
{
return fstat($this->handle);
}
/**
* @return int
*/
public function stream_tell()
{
return ftell($this->handle);
}
/**
* Truncate stream.
*
* Will respond to truncation; e.g., through ftruncate().
*
* @param int $new_size
* The new size.
*
* @return bool
* TRUE on success, FALSE otherwise.
*/
public function stream_truncate($new_size)
{
return ftruncate($this->handle, $new_size);
}
/**
* @return int
*/
public function stream_write($data)
{
return fwrite($this->handle, $data);
}
/**
* @return bool
*/
public function unlink($uri)
{
$this->uri = $uri;
return unlink($this->getLocalPath());
}
/**
* @return array
*/
public function url_stat($uri, $flags)
{
$this->uri = $uri;
$path = $this->getLocalPath();
// Suppress warnings if requested or if the file or directory does not
// exist. This is consistent with PHP's plain filesystem stream wrapper.
if ($flags & STREAM_URL_STAT_QUIET || !file_exists($path)) {
return @stat($path);
} else {
return stat($path);
}
}
/****************************************************以上为php流类原型定义的方法，以下为自定义方法*****************************************/
/**
* 设置流包装器需要操作的主目录
*/
public static function setDirectoryPath($dir = '')
{
if (empty($dir)) {
self::$dir = "./";
}
if (!is_string($dir)) {
trigger_error('DirectoryPath must be string', E_USER_WARNING);
}
self::$dir = $dir;
}
/**
* 得到流包装器需要操作的主目录
*/
public function getDirectoryPath()
{
self::$dir = empty(trim(self::$dir)) ? "./" : (self::$dir);
/*
if (!is_dir(self::$dir)) {
mkdir(self::$dir, 0777, true);
}
//为了方便在实用程序中可以这样做，为标准起见不这样，建立目录不应该是工具库的责任
*/
return self::$dir;
}
/**
* 得到本地文件路径
*/
protected function getLocalPath($uri = null)
{
if (!isset($uri)) {
$uri = $this->uri;
}
$path = $this->getDirectoryPath() . '/' . $this->getTarget($uri);
// In PHPUnit tests, the base path for local streams may be a virtual
// filesystem stream wrapper URI, in which case this local stream acts like
// a proxy. realpath() is not supported by vfsStream, because a virtual
// file system does not have a real filepath.
if (strpos($path, 'vfs://') === 0) {
return $path;
}
$realpath = realpath($path);
if (!$realpath) {
// This file does not yet exist.
$realpath = realpath(dirname($path)) . '/' . basename($path);
}
$directory = realpath($this->getDirectoryPath());
if (!$realpath || !$directory || strpos($realpath, $directory) !== 0) {
return false;
}
return $realpath;
}
/**
* 得到目标
*/
protected function getTarget($uri = null)
{
if (!isset($uri)) {
$uri = $this->uri;
}
list(, $target) = explode('://', $uri, 2);
// Remove erroneous leading or trailing, forward-slashes and backsl ashes.
return trim($target, '\/');
}
}
stream_wrapper_register("yunke", "yunkeWrapper"); //注册yunke流包装器
if (!is_dir("yunke://a/b")) {
mkdir("yunke://a/b", 0777, true); //创建目录是开发者用户的责任
}
if (file_put_contents("yunke://a/b/wrapperTest.txt", "it is a test by:yunke time20161014") !== false) {
echo "ok";
} else {
echo "err";
}
$dir = "yunkenew/subdir"; //再次设定yunke流主目录
yunkeWrapper::setDirectoryPath($dir);
if (!is_dir($dir)) {
mkdir($dir, 0777, true); //创建yunke流的主目录是开发者用户的责任
}
if (file_put_contents("yunke://wrapperTest.txt", "it is a test by:yunke time20161015") !== false) {
echo "ok";
} else {
echo "err";
}
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