从 get_the_post_thumbnail($post->ID) 获取图片源；

我必须从下面的代码中获取图像源。

  $thumburl = get_the_post_thumbnail($post->ID);

我在这里得到

<img width="325" height="202" src="http://localhost/TantraProjects/Border-fall/Repo/WebApp/wp-content/uploads/2012/12/film.png" class="attachment-post-thumbnail wp-post-image" alt="film" title="film">

我想得到这部分。

"http://localhost/TantraProjects/Border-fall/Repo/WebApp/wp-content/uploads/2012/12/film.png"

我怎样才能得到来源？

$post_thumbnail_id = get_post_thumbnail_id($post->ID);
$post_thumbnail_url = wp_get_attachment_url( $post_thumbnail_id );