PHP interface（接口）的示例代码

<?php
class DocumentStore
{
protected $data = [];

public function addDocument(Documentable $document)
{
$key = $document->getId();
$value = $document->getContent();
$this->data[$key] = $value;
}

public function getDocuments()
{
return $this->data;
}

}

interface Documentable
{
public function getId();

public function getContent();
}

class HtmlDocument implements Documentable
{
protected $url;

public function __construct($url)
{
$this->url = $url;
}

public function getId()
{
return $this->url;
}

public function getContent()
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $this->url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 3);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_MAXREDIRS, 3);
$html = curl_exec($ch);
curl_close($ch);

return $html;
}
}

class StreamDocument implements Documentable
{
protected $resource;
protected $buffer;

public function __construct($resource, $buffer = 4096)
{
$this->resource = $resource;
$this->buffer = $buffer;
}

public function getId()
{
return 'resource-' . (int)$this->resource;
}

public function getContent()
{
$streamContent = '';
rewind($this->resource);
while (feof($this->resource) === false){
$streamContent .= fread($this->resource, $this->buffer);
}

return $streamContent;
}
}

class CommandOutputDocument implements Documentable
{
protected $command;

public function __construct($command)
{
$this->command = $command;
}

public function getId()
{
return $this->command;
}

public function getContent()
{
return shell_exec($this->command);
}
}

$documentStore = new DocumentStore();

//添加HTML文档
$htmlDoc = new HtmlDocument('https://php.net');
$documentStore->addDocument($htmlDoc);

//添加流文档
$streamDoc = new StreamDocument(fopen('stream.txt', 'rb'));
$documentStore->addDocument($streamDoc);

//添加终端命令文档
$cmdDoc = new CommandOutputDocument('cat /etc/hosts');
$documentStore->addDocument($cmdDoc);

print_r($documentStore->getDocuments());