xpath:使用 xpath 从节点中提取数据 [英] xpath: extract data from a node using xpath
问题描述
我只想提取销售排名(在本例中为 5)
I want to extract only the sales rank (which in this case is 5)
亚马逊畅销书排名: #5书籍(见图书前 100 名)
来自网页:http://www.amazon.com/Mockingjay-Hunger-Games-Book-3/dp/0439023513/ref=tmm_hrd_title_0
到目前为止,我已经解决了这个问题,它选择了Amazon Best Sellers Rank:":
So far I have gotten down to this, which selects "Amazon Best Sellers Rank:":
//li[@id='SalesRank']/b/text()
我正在使用 PHP DOMDocument
和 DOMXPath
.
I am using PHP DOMDocument
and DOMXPath
.
推荐答案
可以使用纯 XPath:
You can use pure XPath:
substring-before(normalize-space(/html/body//ul/li[@id="SalesRank"]/b[1]/following-sibling::text()[1])," ")
但是,如果您的输入有点混乱,您可能会通过使用 XPath 获取父节点的文本,然后在文本上使用正则表达式来获得您想要的特定内容,从而获得更可靠的结果.
However, if your input is a bit messy you might get more reliable results by using XPath to grab the parent node's text, and then using a regex on the text to get the specific thing you want.
使用 PHP 和 DOMDocument
和 DOMXPath
演示这两种方法:
Demonstration of both methods using PHP with DOMDocument
and DOMXPath
:
// Method 1: XPath only
$xp_salesrank = 'substring-before(normalize-space(/html/body//li[@id="SalesRank"]/b[1]/following-sibling::text()[1])," ")';
// Method 2: XPath and Regex
$regex_ranktext = 'string(/html/body//li[@id="SalesRank"])';
$regex_salesrank = '/Best\s+Sellers\s+Rank:\s*(#\d+)\s+/ui';
// Test URLs
$urls = array(
'http://rads.stackoverflow.com/amzn/click/0439023513',
'http://www.amazon.com/Mockingjay-Final-Hunger-Games-ebook/dp/B003XF1XOQ/ref=tmm_kin_title_0?ie=UTF8&m=AG56TWVU5XWC2',
);
// Results
$ranks = array();
$ranks_regex = array();
foreach ($urls as $url) {
$d = new DOMDocument();
$d->loadHTMLFile($url);
$xp = new DOMXPath($d);
// Method 1: use pure xpath
$ranks[] = $xp->evaluate($xp_salesrank);
// Method 2: use xpath to get a section of text, then regex for more specific item
// This method is probably more forgiving of bad HTML.
$rank_regex = '';
$ranktext = $xp->evaluate($regex_ranktext);
if ($ranktext) {
if (preg_match($regex_salesrank, $ranktext, $matches)) {
$rank_regex = $matches[1];
}
}
$ranks_regex[] = $rank_regex;
}
assert($ranks===$ranks_regex); // Both methods should be the same.
var_dump($ranks);
var_dump($ranks_regex);
我得到的输出是:
array(2) {
[0]=>
string(2) "#4"
[1]=>
string(2) "#3"
}
array(2) {
[0]=>
string(2) "#4"
[1]=>
string(2) "#3"
}
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