PHP 正则获取字符串的URL

<?php
header("charset=utf-8;");
$str ='阅谁问君诵，水落清香浮，http://onestopweb.iteye.com/,一共享共享网站。<img src="http://www.iteye.com/">'; 
preg_match_all("/http:[\/]{2}[a-z]+[.]{1}[a-z\d\-]+[.]{1}[a-z\d]*[\/]*[A-Za-z\d]*[\/]*[A-Za-z\d]*/",$str,$arr);  
print_r($arr); 

效果图：