获取指定URl页面中所有链接

	//获取指定URL页面中所有链接
	function get_url_href($url){
		$html = file_get_contents($url);
		$dom = new DOMDocument();
		@$dom->loadHTML($html);
		$xpath = new DOMXPath($dom);
		$hrefs = $xpath->evaluate('/html/body//a');
		for($i=0;$ilength;$i++){
			$href = $hrefs->item($i);
			$url = $href->getAttribute('href');
			if(substr($url,0,4) == 'http') echo $url.'
';
		}
	}