Python urllib.request和urllib.error用法

import urllib.request

response = urllib.request.urlopen('http://www.example.com')
html = response.read().decode('utf-8')
print(html)

import urllib.request
import urllib.parse

data = urllib.parse.urlencode({'key1': 'value1', 'key2': 'value2'}).encode('utf-8')
req = urllib.request.Request(url, data=data, method='POST')
response = urllib.request.urlopen(req)

import urllib.request

url = 'http://www.example.com/file.txt'
urllib.request.urlretrieve(url, 'local_file.txt')

import urllib.request
import urllib.error

try:
    response = urllib.request.urlopen('http://www.example.com')
except urllib.error.HTTPError as e:
    print('HTTPError:', e.code, e.reason)
except urllib.error.URLError as e:
    print('URLError:', e.reason)

import urllib.request
import urllib.error

try:
    response = urllib.request.urlopen('http://www.example.com')
except urllib.error.HTTPError as e:
    print('HTTPError:', e)
    print('HTTPError code:', e.code)
    print('HTTPError reason:', e.reason)
    print('HTTPError headers:', e.headers)