PHP｜PHP的接口使用示例

举个Demo来说明接口的作用。

有这么一个类。

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;
    }
}

其中Documentable就是接口。定义如下：

interface Documentable
{
    public function getId();
    
    public function getContent();
}

在未来的业务开发中，我们不必关心具体的Document的获取场景，只需要确定，这个Document实现了这个接口，拥有这两个方法即可。实现了业务细节和整体架构抽象的解耦。

举个例子：

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);
        // opt etc
        $html = curl_exec($ch);
        curl_close($ch);
        
        return $htl;
    }
}

再举个例子：

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;
    }
}

再举个例子:

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);
    }
}

使用方法：

<?php

$documentStore = new DocumentStore();

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

$streamDoc = new StreamDocument(fopen('stream.txt', 'rb'));
$streamDoc->addDocument($streamDoc);

$cmdDoc = new CommandOutputDocument('cat /etc/hosts');
$documentStore->addDocument($cmdDoc);

print_r($documentStore->getDocuments());

参考：

1. Modern PHP