public static void main(String[] args) {
		BDBFrontier frontier =null;
		try {
			frontier =new BDBFrontier("bdb");
			CrawlUrl url =new CrawlUrl();
			url.setOriUrl("http://www.sina.com");
			frontier.putUrl(url);
			System.out.println(frontier.getNext().getOriUrl());
		} catch (DatabaseException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (frontier !=null) frontier.close();
		}
	}