我知道我可以使用PHP stream函数从文件名(真实的或URL)创建fopen:
$stream = fopen('php://temp', 'r');
结果流($stream
)是"流" 类型的资源,由网址{{1}创建}。
但我如何从资源中创建如上所述的流?
我为什么要问这个?
我正在使用PSR-7库,我使用php://temp
类实现了PSR-7 StreamInterface。为了创建Stream
个实例,我决定实现Stream
。其界面StreamFactory
在PSR-17 (HTTP Factories)提案中定义。
StreamFactoryInterface
定义了一个名为StreamFactoryInterface
的方法,该方法符合其官方评论 - 应该:
从现有资源创建新流。
流必须是可读的并且可以是可写的。
因此工厂方法接收资源作为参数。并且,在其具体实现中,创建了一个新的createStreamFromResource
对象 - 它也接收资源作为参数。
以下是问题:
为简单起见,我们假设Stream
类仅适用于流,例如:使用" stream" 类型的资源。如果它收到的资源不属于" stream" ,则拒绝该资源。
那么,如果Stream
的资源参数不是" stream" 类型的资源,该怎么办?如何将其转换为流,例如进入" stream" 类型的资源,以便我可以进一步传递它,以便用它来创建一个新的createStreamFromResource
对象?是否有实现此任务的方法(PHP方法,函数或可能的转换函数)?
备注:
Stream
),说明我如何创建一个流,例如一个testStream.php
实例,有三种方式:一次直接,两次使用流工厂。Stream
和方法StreamFactory
。调用此方法应该是我在createStreamFromResource
中创建流的第四种方式。testStream.php
和Stream
,以便您可以直接测试所有课程,如果您愿意的话。这两个类是我真实代码的一个非常简化的版本。非常感谢您的时间和耐心!
Response
<?php
use Tests\Stream;
use Tests\Response;
use Tests\StreamFactory;
/*
* ================================================
* Option 1: Create a stream by a stream name
* (like "php://temp") with read and write rights.
* ================================================
*/
$stream = new Stream('php://temp', 'w+b');
$response = new Response($stream);
$response->getBody()->write(
'Stream 1: Created directly.<br/><br/>'
);
echo $response->getBody();
/*
* ================================================
* Option 2: Create a stream by a stream name
* (like "php://temp"), using a stream factory.
* ================================================
*/
$streamFactory = new StreamFactory();
$stream = $streamFactory->createStreamFromFile('php://temp', 'w+b');
$response = new Response($stream);
$response->getBody()->write(
'Stream 2: Created by a stream name, with a stream factory.<br/><br/>'
);
echo $response->getBody();
/*
* ================================================
* Option 3: Create a stream from a string, using a
* stream factory.
* ================================================
*/
$streamFactory = new StreamFactory();
$stream = $streamFactory->createStream(
'Stream 3: Created from a string, with a stream factory.<br/><br/>'
);
$response = new Response($stream);
echo $response->getBody();
/*
* ================================================
* Option 4: Create a stream from an existing
* resource, using a stream factory.
* ================================================
*
* @asking How can I create a stream by calling the
* the factory method ServerFactory::createStreamFromResource
* with a resource which is not of type "stream"?
*/
//...
<?php
namespace Tests;
use Tests\Stream;
use Psr\Http\Message\StreamInterface;
use Psr\Http\Message\StreamFactoryInterface;
class StreamFactory implements StreamFactoryInterface {
/**
* Create a new stream from an existing resource.
*
* The stream MUST be readable and may be writable.
*
* @param resource $resource
*
* @return StreamInterface
* @throws \InvalidArgumentException
*/
public function createStreamFromResource($resource) {
/*
* @asking What if $resource is not already a resource of type *"stream"*?
* How can I transform it into a stream, e.g. into a resource of type *"stream"*,
* so that I can pass it further, to the call for creating a new `Stream` object
* with it? Is there a way (a PHP method, a function, or maybe a casting function)
* of achieving this task?
*/
//...
return new Stream($resource, 'w+b');
}
/**
* Create a new stream from a string.
*
* The stream SHOULD be created with a temporary resource.
*
* @param string $content
*
* @return StreamInterface
* @throws \InvalidArgumentException
*/
public function createStream($content = '') {
if (!isset($content) || !is_string($content)) {
throw new \InvalidArgumentException('For creating a stream, a content string must be provided!');
}
$stream = $this->createStreamFromFile('php://temp', 'w+b');
$stream->write($content);
return $stream;
}
/**
* Create a stream from an existing file.
*
* The file MUST be opened using the given mode, which may be any mode
* supported by the `fopen` function.
*
* The `$filename` MAY be any string supported by `fopen()`.
*
* @param string $filename
* @param string $mode
*
* @return StreamInterface
*/
public function createStreamFromFile($filename, $mode = 'r') {
return new Stream($filename, $mode);
}
}
<?php
namespace Tests;
use Psr\Http\Message\StreamInterface;
class Stream implements StreamInterface {
/**
* Stream (resource).
*
* @var resource
*/
private $stream;
/**
*
* @param string|resource $stream Stream name, or resource.
* @param string $accessMode (optional) Access mode.
* @throws \InvalidArgumentException
*/
public function __construct($stream, string $accessMode = 'r') {
if (
!isset($stream) ||
(!is_string($stream) && !is_resource($stream))
) {
throw new \InvalidArgumentException(
'The provided stream must be a filename, or an opened resource of type "stream"!'
);
}
if (is_string($stream)) {
$this->stream = fopen($stream, $accessMode);
} elseif (is_resource($stream)) {
if ('stream' !== get_resource_type($stream)) {
throw new \InvalidArgumentException('The provided resource must be of type "stream"!');
}
$this->stream = $stream;
}
}
/**
* Write data to the stream.
*
* @param string $string The string that is to be written.
* @return int Returns the number of bytes written to the stream.
* @throws \RuntimeException on failure.
*/
public function write($string) {
return fwrite($this->stream, $string);
}
/**
* Reads all data from the stream into a string, from the beginning to end.
*
* @return string
*/
public function __toString() {
try {
// Rewind the stream.
fseek($this->stream, 0);
// Get the stream contents as string.
$contents = stream_get_contents($this->stream);
return $contents;
} catch (\RuntimeException $exc) {
return '';
}
}
public function close() {}
public function detach() {}
public function eof() {}
public function getContents() {}
public function getMetadata($key = null) {}
public function getSize() {}
public function isReadable() {}
public function isSeekable() {}
public function isWritable() {}
public function read($length) {}
public function rewind() {}
public function seek($offset, $whence = SEEK_SET) {}
public function tell() {}
}
答案 0 :(得分:1)
您可以按照自己喜欢的方式实现它,但此方法实际上只是预生成资源的包装器。
在大多数情况下,你的Stream可能会接受一个字符串,可能还有一个settings / options数组,并根据信息创建一个流(可能在途中某处有一个fopen('http://...')
。
createStreamFromResource($ resource)将接收预先生成的资源(例如,来自fopen
的返回资源值而不是执行fopen
的数据):
class Stream implements StreamInterface {
// ...
public function __construct($url, $opt = null) {
// ...
if( is_resource( $url ) ) {
/*
* Check that the $resource is a valid resource
* (e.g. an http request from an fopen call vs a mysql resource.)
* or possibly a stream context that still needs to create a
* request...
*/
if( !$isValid ) {
return false;
}
$this->resource = $resource;
} else {
// ...
$this->resource = fopen($url, $modifiedOpt);
// ...
}
}
// ...
/* createStreamFromResource would call Stream::fromResource($r)
* or possibly Stream($resource) directly, your call.
*/
static function fromResource($resource) {
return new static($resource);
}
}
您的工厂方法可能很简单:
public function createStreamFromResource($resource) {
return Stream::fromResource($resource);
}
答案 1 :(得分:1)
PSR-7有很多很好的实现StreamInterface
我建议先看一下。您可能会了解需要进行何种验证和逻辑。
StreamInterface
<强>更新强>: 在查看所有这些链接后,我发现了您当前代码的一些问题:
您必须在构造函数中检查资源类型。例如,它可能是一个MySQL资源,你不想写它:
public function __construct($stream, string $accessMode = 'r') {
if (is_string($stream)) {
$stream = fopen($stream, $accessMode);
}
if (! is_resource($stream) || 'stream' !== get_resource_type($stream)) {
throw new InvalidArgumentException(
'Invalid stream provided; must be a string stream identifier or stream resource'
);
}
$this->stream = $stream;
}
写入流时,检查流是否实际可写。您必须先实施isWritable
方法,然后在write
函数中调用它。此示例取自zend-diactoros库:
public function isWritable()
{
if (! $this->resource) {
return false;
}
$meta = stream_get_meta_data($this->resource);
$mode = $meta['mode'];
return (
strstr($mode, 'x')
|| strstr($mode, 'w')
|| strstr($mode, 'c')
|| strstr($mode, 'a')
|| strstr($mode, '+')
);
}
与read
和seek
功能相同,您必须首先实施isSeekable
和isReadable
。
__toString
还应检查流是否可读且可搜索:
public function __toString()
{
if (! $this->isReadable()) {
return '';
}
try {
if ($this->isSeekable()) {
$this->rewind();
}
return $this->getContents();
} catch (RuntimeException $e) {
return '';
}
}
希望这会有所帮助。祝你的新图书馆好运。
答案 2 :(得分:1)
如何处理传递的参数取决于您的最终实现。如果你的代码需要一个流参数,那么它应该在它没有检测到这种情况时停止。但是,如果您的代码需要处理该问题,那么您可以尝试创建一个流。
修改强>
从一开始就没有得到它,但看起来问题是如果有可能转换资源变量。根据{{3}},这是不可能的,没有意义。