PHP相关作业（三个lab，一个Assignment）

# PSR-7 Message Implementation This repository contains a full [PSR-7](http://www.php-fig.org/psr/psr-7/) message implementation, several stream decorators, and some helpful functionality like query string parsing. [](https://travis-ci.org/guzzle/psr7) # Stream implementation This package comes with a number of stream implementations and stream decorators. ## AppendStream `GuzzleHttp\Psr7\AppendStream` Reads from multiple streams, one after the other. ```php use GuzzleHttp\Psr7; $a = Psr7\Utils::streamFor('abc, '); $b = Psr7\Utils::streamFor('123.'); $composed = new Psr7\AppendStream([$a, $b]); $composed->addStream(Psr7\Utils::streamFor(' Above all listen to me')); echo $composed; // abc, 123. Above all listen to me. ``` ## BufferStream `GuzzleHttp\Psr7\BufferStream` Provides a buffer stream that can be written to fill a buffer, and read from to remove bytes from the buffer. This stream returns a "hwm" metadata value that tells upstream consumers what the configured high water mark of the stream is, or the maximum preferred size of the buffer. ```php use GuzzleHttp\Psr7; // When more than 1024 bytes are in the buffer, it will begin returning // false to writes. This is an indication that writers should slow down. $buffer = new Psr7\BufferStream(1024); ``` ## CachingStream The CachingStream is used to allow seeking over previously read bytes on non-seekable streams. This can be useful when transferring a non-seekable entity body fails due to needing to rewind the stream (for example, resulting from a redirect). Data that is read from the remote stream will be buffered in a PHP temp stream so that previously read bytes are cached first in memory, then on disk. ```php use GuzzleHttp\Psr7; $original = Psr7\Utils::streamFor(fopen('http://www.google.com', 'r')); $stream = new Psr7\CachingStream($original); $stream->read(1024); echo $stream->tell(); // 1024 $stream->seek(0); echo $stream->tell(); // 0 ``` ## DroppingStream `GuzzleHttp\Psr7\DroppingStream` Stream decorator that begins dropping data once the size of the underlying stream becomes too full. ```php use GuzzleHttp\Psr7; // Create an empty stream $stream = Psr7\Utils::streamFor(); // Start dropping data when the stream has more than 10 bytes $dropping = new Psr7\DroppingStream($stream, 10); $dropping->write('01234567890123456789'); echo $stream; // 0123456789 ``` ## FnStream `GuzzleHttp\Psr7\FnStream` Compose stream implementations based on a hash of functions. Allows for easy testing and extension of a provided stream without needing to create a concrete class for a simple extension point. ```php use GuzzleHttp\Psr7; $stream = Psr7\Utils::streamFor('hi'); $fnStream = Psr7\FnStream::decorate($stream, [ 'rewind' => function () use ($stream) { echo 'About to rewind - '; $stream->rewind(); echo 'rewound!'; } ]); $fnStream->rewind(); // Outputs: About to rewind - rewound! ``` ## InflateStream `GuzzleHttp\Psr7\InflateStream` Uses PHP's zlib.inflate filter to inflate deflate or gzipped content. This stream decorator skips the first 10 bytes of the given stream to remove the gzip header, converts the provided stream to a PHP stream resource, then appends the zlib.inflate filter. The stream is then converted back to a Guzzle stream resource to be used as a Guzzle stream. ## LazyOpenStream `GuzzleHttp\Psr7\LazyOpenStream` Lazily reads or writes to a file that is opened only after an IO operation take place on the stream. ```php use GuzzleHttp\Psr7; $stream = new Psr7\LazyOpenStream('/path/to/file', 'r'); // The file has not yet been opened... echo $stream->read(10); // The file is opened and read from only when needed. ``` ## LimitStream `GuzzleHttp\Psr7\LimitStream` LimitStream can be used to read a subset or slice of an existing stream object. This can be useful for breaking a large file into smaller pieces to be sent in chunks (e.g. Amazon S3's multipart upload API). ```php use GuzzleHttp\Psr7; $original = Psr7\Utils::streamFor(fopen('/tmp/test.txt', 'r+')); echo $original->getSize(); // >>> 1048576 // Limit the size of the body to 1024 bytes and start reading from byte 2048 $stream = new Psr7\LimitStream($original, 1024, 2048); echo $stream->getSize(); // >>> 1024 echo $stream->tell(); // >>> 0 ``` ## MultipartStream `GuzzleHttp\Psr7\MultipartStream` Stream that when read returns bytes for a streaming multipart or multipart/form-data stream. ## NoSeekStream `GuzzleHttp\Psr7\NoSeekStream` NoSeekStream wraps a stream and does not allow seeking. ```php use GuzzleHttp\Psr7; $original = Psr7\Utils::streamFor('foo'); $noSeek = new Psr7\NoSeekStream($original); echo $noSeek->read(3); // foo var_export($noSeek->isSeekable()); // false $noSeek->seek(0); var_export($noSeek->read(3)); // NULL ``` ## PumpStream `GuzzleHttp\Psr7\PumpStream` Provides a read only stream that pumps data from a PHP callable. When invoking the provided callable, the PumpStream will pass the amount of data requested to read to the callable. The callable can choose to ignore this value and return fewer or more bytes than requested. Any extra data returned by the provided callable is buffered internally until drained using the read() function of the PumpStream. The provided callable MUST return false when there is no more data to read. ## Implementing stream decorators Creating a stream decorator is very easy thanks to the `GuzzleHttp\Psr7\StreamDecoratorTrait`. This trait provides methods that implement `Psr\Http\Message\StreamInterface` by proxying to an underlying stream. Just `use` the `StreamDecoratorTrait` and implement your custom methods. For example, let's say we wanted to call a specific function each time the last byte is read from a stream. This could be implemented by overriding the `read()` method. ```php use Psr\Http\Message\StreamInterface; use GuzzleHttp\Psr7\StreamDecoratorTrait; class EofCallbackStream implements StreamInterface { use StreamDecoratorTrait; private $callback; public function __construct(StreamInterface $stream, callable $cb) { $this->stream = $stream; $this->callback = $cb; } public function read($length) { $result = $this->stream->read($length); // Invoke the callback when EOF is hit. if ($this->eof()) { call_user_func($this->callback); } return $result; } } ``` This decorator could be added to any existing stream and used like so: ```php use GuzzleHttp\Psr7; $original = Psr7\Utils::streamFor('foo'); $eofStream = new EofCallbackStream($original, function () { echo 'EOF!'; }); $eofStream->read(2); $eofStream->read(1); // echoes "EOF!" $eofStream->seek(0); $eofStream->read(3); // echoes "EOF!" ``` ## PHP StreamWrapper You can use the `GuzzleHttp\Psr7\StreamWrapper` class if you need to use a PSR-7 stream as a PHP stream resource. Use the `GuzzleHttp\Psr7\StreamWrapper::getResource()` method to create a PHP stream from a PSR-7 stream. ```php use GuzzleHttp\Psr7\StreamWrapper; $stream = GuzzleHttp\Psr7\Utils::streamFor('hello!'); $resource = StreamWrapper::getResource($stream); echo fread($resource, 6); // outputs hello! ``` # Static API There are various static methods available under the `GuzzleHttp\Psr7` namespace. ## `GuzzleHttp\Psr7\Message::toString` `public static function toString(MessageInterface $message): string` Returns the string representation of an HTTP message. ```php $request = new GuzzleHttp\Psr7\Request('GET', 'http://example.com'); echo GuzzleHttp\Psr7\Message::toString($request); ``` ## `GuzzleHttp\Psr7\Message::bodySummary` `public static function bodySummary(MessageInterface $message, int $truncateAt = 120): string|null` Get a short summary of the message body. Will return `null` if the response is not printable. ## `GuzzleHttp\Psr7\Message::rewindBody` `public static