python3:urllib.request 的主要函式說明

內容的主要來源為：

https://docs.python.org/3/library/urllib.request.html#module-urllib.request

The urllib.request module defines functions and classes which help in opening URLs (mostly HTTP) in a complex world — basic and digest authentication, redirections, cookies and more.

urllib.request.urlopen(url, data=None, [timeout, ]*, cafile=None, capath=None, cadefault=False, context=None)

url, which can be either a string or a Request object.
     url 既可以是一個string, 也可以是一個request物件
data must be an object specifying additional data to be sent to the server, or None if no such data is needed. See Request for details
     data 必須是指定傳送給sever的特定附加資料, 當這個資料不需要，則data=None
函式返回的是什麼？
This function always returns an object which can work as a context manager and has methods such as

這個函式總是返回一個可以作為上下文的管理器.並有如下的方法:

例項如下：

from urllib import request

if __name__ == '__main__':
    url = 'http://www.baidu.com/'
    response = request.urlopen(url)
    html = response.read().decode('utf-8')
    print(html)

其它幾個函式的例項如下(from ipython)