如何显示从外部网站获取的内容？

Question

How do I grab pieces of content from external websites and display them on my website? (Similar to what an RSS feed or other aggregator does).

For example, say I want to display items from another website's calendar:

Other website:

<h1>Here's our calendar:</h1>

<div class="calendar_item">
  <h2>Boston Marathon</h2>
  <p class="date">June 23, 2012</p>
  <p class="description">This marathon is 26.2 miles and lots of fun.</p>
</div>

<div class="calendar_item">    
  <h2>Irish Pub Crawl</h2>
  <p class="date">July 17, 2012</p>
  <p class="description">Shamrocks and green things are super-fun.</p>
</div>

<div class="calendar_item">
  <h2>Tim's Birthday</h2>
  <p class="date">August 25, 2012</p>
  <p class="description">It's Tim's birthday, yo.</p>
</div>

My website:

<h1>Here's a feed of some calendar items from someone else's website:</h1>

<div class="event_title">Boston Marathon</div>
<div class="event_date">June 23, 2012</div>
<div class="event_description">This marathon is 26.2 miles and lots of fun.</div>

<div class="event_title">Irish Pub Crawl</div>
<div class="event_date">July 17, 2012</div>
<div class="event_description">Shamrocks and green things are super-fun.</div>

<div class="event_title">Tim's Birthday</div>
<div class="event_date">August 25, 2012</div>
<div class="event_description">It's Tim's birthday, yo.</div>

Here's what I've tried (using MAMP):

<?php

$url = "http://example.com";

$page = curl($url);

$pattern = '%
<h2>(.+?)</h2>
%i';

preg_match($pattern,$page,$matches);

print_r($matches);

?>

...which prints:

Array ( )

The tutorials/etc. I've viewed include ambiguous answers like "try cURL". This seems so simple, but I'm a stumped noob.

Thanks in advance, guys :)

Answer 1

I would not recommend regex for parsing HTML. PHP 5+ comes with a parser which you can use as shown below.

$content = file_get_contents('test.html');
$doc = 
<<<DOC
$content
DOC;
$dom = new DOMDocument();
$dom->loadHTML($doc);
$h2Tags = $dom->getElementsByTagName("h2");
$pTags = $dom->getElementsByTagName("p");
foreach($h2Tags as $h2 ) {
    //do something
}

foreach($pTags as $p ) {
if($p->getAttribute("class") == "date") {
    //do something
}

}

$h2 is of type DOMElement. It inherits DOMNode. So you can use nodeValue property to access the values. In the above example, you can write $h2->nodeValue to access the content.