PHP简单的HTML DOM解析器

Question

I am working with simple web crawler. Below is simple html code i used to learn.

input.php

<ul id="nav">
    <li>
        <a href="www.google.com">Google</a>
        <ul>
            <li>
                <a href="mail.gmail.com">Gmail</a>
            </li>
        </ul>
    </li>
    <li>
        <a href="www.yahoo.com">Yahoo</a>
        <ul>
            <li>
                <a href="mail.yahoo.com">Yahoo Mail</a>
            </li>
        </ul>
    </li>
</ul>

I need to crawl the first anchor tag in ul[id=nav]->li. The code i used to crawl input.php is

<?php
    include 'simple_html_dom.php';
    $html = file_get_html('input.php');

    foreach ($html->find('ul[id=nav]') as $navUL){
        foreach ($navUL->find('li') as $navUL_LI){
            echo $navUL_LI->find('a',0)->outertext."<br>";              
        }
    }
?>

It Displays all the anchor tag in my input.php. I need to display only google and yahoo. How can i achieve this?

Answer 1

In this case you can directly point it out with children() method. Example:

foreach($html->find('ul#nav') as $ul) {
    foreach($ul->children() as $li) {
        echo $li->children(0)->outertext . '<br/>';
    }
}

Alternatively, you can use DOMDocument + DOMXpath for this too:

$dom = new DOMDocument();
$dom->loadHTML($str);
$xpath = new DOMXpath($dom);
// directly target those links
$links = $xpath->query('//ul[@id="nav"]/li/a');

foreach($links as $a) {
    echo $a->nodeValue . '<br/>';
}