使用PHP实现RSS订阅功能

RSS（Really Simple Syndication）订阅源有一种规范的 XML 格式，通常称为 RSS feed。这个规范定义了一种结构化的 XML 文档格式，用于发布网站内容更新的摘要信息，供用户订阅和阅读。

RSS 订阅源的规范格式通常包括以下基本元素：

1. <channel>：包含整个 RSS 订阅源的信息，如标题、链接、描述等。
2. <item>：包含单个内容项的信息，如标题、链接、发布日期、描述等。
3. 其他元素：如标题、链接、描述、发布日期等，用于描述每个内容项的具体信息。

一、生成 RSS

class RssFeed {
    private $channelTitle;
    private $channelLink;
    private $channelDescription;
    private $items;

    public function __construct($title, $link, $description) {
        $this->channelTitle = $title;
        $this->channelLink = $link;
        $this->channelDescription = $description;
        $this->items = array();}

    public function addItem($title, $link, $description, $pubDate) {$this->items[] = array(
            "title" => $title,
            "link" => $link,
            "description" => $description,
            "pubDate" => $pubDate
        );
    }

    public function generateFeed()
    {header("Content-type: application/xml; charset=utf-8");

        $xml = '<?xml version="1.0"encoding="UTF-8"?>';

        $xml .= '<rss version="2.0">';
        $xml .= '<channel>';
        $xml .= '<title>'.$this->channelTitle.'</title>';
        $xml .= '<link>'.$this->channelLink.'</link>';
        $xml .= '<description>'.$this->channelDescription.'</description>';
        $xml .= '<language>en-us</language>';

        foreach ($this->items as $item) {
            $xml .= '<item>';
            $xml .= '<title>'.$item['title'].'</title>';
            $xml .= '<link>'.$item['link'].'</link>';
            $xml .= '<description>'.$item['description'].'</description>';
            $xml .= '<pubDate>'.$item['pubDate'].'</pubDate>';
            $xml .= '</item>';
        }
        $xml .= '</channel>';
        $xml .= '</rss>';

        echo $xml;
    }
}

// 创建 RssFeed 实例
$rss = new RssFeed("Your Channel Title", "http://www.example.com", "Your channel description");

// 添加内容项
$rss->addItem("Item 1 Title", "http://www.example.com/item1", "This is the description of item 1", "Wed, 02 Oct 2021 08:00:00 GMT");
$rss->addItem("Item 2 Title", "http://www.example.com/item2", "This is the description of item 2", "Thu, 03 Oct 2021 08:00:00 GMT");

// 生成并输出 RSS 订阅源
$rss->generateFeed();

二、解析 RSS 订阅源

class RSS {
    private $url;
    public function __construct($url) {$this->url = $url;}
    public function get_feed() {$xml = simplexml_load_file($this->url);
        $feed = array('title' => (string) $xml->channel->title,
            'description' => (string) $xml->channel->description,
            'items' => array(),);
        foreach($xml->channel->item as $item) {$feed['items'][] = array('title' => (string) $item->title,
                'description' => (string) $item->description,
                'link' => (string) $item->link,
                'date' => (string) $item->pubDate,
            );
        }
        return $feed;
    }
}

$rss = new Rss('https://www.bomx.cn/feed');
var_dump($rss->get_feed());