有问题的代码：

import urllib.request
# 代码002：(未声明headers，会报错）
response = urllib.request.urlopen("http://www.baidu.com")
print(response)
print(response.read())

运行结果：

Traceback (most recent call last):
  File "D:/PycharmProjects/pythonProject/douban/test1/temp.py", line 11, in <module>
    response = urllib.request.urlopen("http://www.baidu.com")
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\urllib\request.py", line 222, in urlopen
    return opener.open(url, data, timeout)
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\urllib\request.py", line 525, in open
    response = self._open(req, data)
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\urllib\request.py", line 542, in _open
    result = self._call_chain(self.handle_open, protocol, protocol +
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\urllib\request.py", line 502, in _call_chain
    result = func(*args)
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\urllib\request.py", line 1379, in http_open
    return self.do_open(http.client.HTTPConnection, req)
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\urllib\request.py", line 1354, in do_open
    r = h.getresponse()
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\http\client.py", line 1332, in getresponse
    response.begin()
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\http\client.py", line 303, in begin
    version, status, reason = self._read_status()
  File "C:\Users\lord\AppData\Local\Programs\Python\Python38-32\lib\http\client.py", line 272, in _read_status
    raise RemoteDisconnected("Remote end closed connection without"
http.client.RemoteDisconnected: Remote end closed connection without response

中文翻译：

raise RemoteDisconnected("Remote end closed connection without http.client.RemoteDisconnected: Remote end closed connection without response
远程端未连接（没有http服务器，远程端关闭连接），远程端关闭连接，无响应。

解决方法：

网络参考资源：

网址：《爬虫过程报错：http.client.RemoteDisconnected: Remote end closed connection without response》

利用 urllib 发起的请求，UA 默认是 Python-urllib/3.5 而在 chrome 中访问 UA 则是 User-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36，因为服务器根据 UA 来判断拒绝了 python 爬虫。
把 python 伪装成 chrome 去获取糗百的网页，可以顺利的得到数据。

修改后的代码：

import urllib.request

headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36'}
# 代码001：
data1 = urllib.request.Request("https://www.bilibili.com", headers=headers)
data2 = urllib.request.urlopen(data1).read()
data3 = urllib.request.urlopen(data1)
data4 = urllib.request.urlopen(data1).read().decode('utf-8') #转码
print(data2)
# print(data3)
# print(data4)

# 代码002：(未声明headers，会报错）
# response = urllib.request.urlopen("http://www.baidu.com")
# print(response)
# print(response.read())

headers 获取方法（google）：

打开google浏览器，查看网页源代码

网络参考资源：
《python爬虫-通过chrome浏览器查看当前网页的http头》