如何使用PHP检查URL是外部URL还是内部URL？

Question

我正在通过这个循环获取页面的所有ahref:

foreach($html->find('a[href!="#"]') as $ahref) {
    $ahrefs++;
}

我想做这样的事情:

foreach($html->find('a[href!="#"]') as $ahref) {
    if(isexternal($ahref)) {
        $external++;
    }
    $ahrefs++;
}

外在的地方是一个功能

function isexternal($url) {
    // FOO...

    // Test if link is internal/external
    if(/*condition is true*/) {
        return true;
    }
    else {
        return false;
    }
}

救命!

Answer 1

使用parse_url并将主机与本地主机进行比较(通常但并不总是与之相同$_SERVER['HTTP_HOST'])

function isexternal($url) {
  $components = parse_url($url);    
  return !empty($components['host']) && strcasecmp($components['host'], 'example.com'); // empty host will indicate url like '/relative.php'
}

Hovewer这将把www.example.com和example.com视为不同的主机.如果您希望将所有子域都视为本地链接,那么该函数将会更大一些:

function isexternal($url) {
  $components = parse_url($url);
  if ( empty($components['host']) ) return false;  // we will treat url like '/relative.php' as relative
  if ( strcasecmp($components['host'], 'example.com') === 0 ) return false; // url host looks exactly like the local host
  return strrpos(strtolower($components['host']), '.example.com') !== strlen($components['host']) - strlen('.example.com'); // check if the url host is a subdomain
}