How do you strip out the domain name from a URL in

问题:

Im looking for a method (or function) to strip out the domain.ext part of any URL thats fed into the function. The domain extension can be anything (.com, .co.uk, .nl, .whatever), and the URL thats fed into it can be anything from http://www.domain.com to www.domain.com/path/script.php?=whatever

Whats the best way to go about doing this?

回答1:

parse_url turns a URL into an associative array:

php > $foo = "http://www.example.com/foo/bar?hat=bowler&accessory=cane";
php > $blah = parse_url($foo);
php > print_r($blah);
Array
(
    [scheme] => http
    [host] => www.example.com
    [path] => /foo/bar
    [query] => hat=bowler&accessory=cane
)

回答2:

You can use parse_url() to do this:

$url = 'http://www.example.com';
$domain = parse_url($url, PHP_URL_HOST);
$domain = str_replace('www.','',$domain);

In this example, $domain should contain example.com, irrespective of it having www or not. It also works for a domain such as .co.uk

回答3:

You can also write a regular expression to get exactly what you want.

Here is my attempt at it:

$pattern = '/\w+\..{2,3}(?:\..{2,3})?(?:$|(?=\/))/i';
$url = 'http://www.example.com/foo/bar?hat=bowler&accessory=cane';
if (preg_match($pattern, $url, $matches) === 1) {
    echo $matches[0];
}

The output is:

example.com

This pattern also takes into consideration domains such as 'example.com.au'.

Note: I have not consulted the relevant RFC.

回答4:

Here are a couple simple functions to get the root domain (example.com) from a normal or long domain (test.sub.domain.com) or url (http://www.example.com).

/**
 * Get root domain from full domain
 * @param string $domain
 */
public function getRootDomain($domain)
{
    $domain = explode('.', $domain);

    $tld = array_pop($domain);
    $name = array_pop($domain);

    $domain = "$name.$tld";

    return $domain;
}

/**
 * Get domain name from url
 * @param string $url
 */
public function getDomainFromUrl($url)
{
    $domain = parse_url($url, PHP_URL_HOST);
    $domain = $this->getRootDomain($domain);

    return $domain;
}

回答5:

Solved this...

Say we're calling dev.mysite.com and we want to extract 'mysite.com'

$requestedServerName = $_SERVER['SERVER_NAME']; // = dev.mysite.com

$thisSite = explode('.', $requestedServerName); // site name now an array

array_shift($thisSite); //chop off the first array entry eg 'dev'

$thisSite = join('.', $thisSite); //join it back together with dots ;)

echo $thisSite; //outputs 'mysite.com'

Works with mysite.co.uk too so should work everywhere :)

回答6:

I spent some time thinking about whether it makes sense to use a regular expression for this, but in the end I think not.

firstresponder's regexp came close to convincing me it was the best way, but it didn't work on anything missing a trailing slash (so http://example.com, for instance). I fixed that with the following: '/\w+\..{2,3}(?:\..{2,3})?(?=[\/\W])/i', but then I realized that matches twice for urls like 'http://example.com/index.htm'. Oops. That wouldn't be so bad (just use the first one), but it also matches twice on something like this: 'http://abc.ed.fg.hij.kl.mn/', and the first match isn't the right one. :(

A co-worker suggested just getting the host (via parse_url()), and then just taking the last two or three array bits (split() on '.') The two or three would be based on a list of domains, like 'co.uk', etc. Making up that list becomes the hard part.

回答7:

There is only one correct way to extract domain parts, it's use Public Suffix List (database of TLDs). I recomend TLDExtract package, here is sample code:

$extract = new LayerShifter\TLDExtract\Extract();

$result = $extract->parse('www.domain.com/path/script.php?=whatever');
$result->getSubdomain(); // will return (string) 'www'
$result->getHostname(); // will return (string) 'domain'
$result->getSuffix(); // will return (string) 'com'