* handle_starttage(tag, attrs)
* handle_startendtage(tag, attrs)
* handle_endtage(tag)
更改上述函数来实现自己需要的功能
* tag是html标签，
* attrs是(属性，值)元组的list
* HTMLParser自动将tag和attrs都转为小写
def handle_starttag(self, tag, attrs):
#print "Encountered the beginning of a %s tag" % tag
if tag == "a":
if len(attrs) == 0: pass
else:
for (variable, value) in attrs:
if variable == "href":
self.links.append(value)