利用Python正则表达式匹配字符串中的http链接。主要难点是用正则表示出http 链接的模式。

import re
pattern = re.compile(r'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+')    # 匹配模式

string = 'Its after 12 noon, do you know where your rooftops are? http://tinyurl.com/NYCRooftops '
url = re.findall(pattern,string)
print url

>>['http://tinyurl.com/NYCRooftops']