問題：
執行下面的語句時
1 def set_IPlsit(): 2 url = 'https://www.whatismyip.com/' 3 response = urllib.request.urlopen(url) 4 html = response.read().decode('utf-8')
出現以下異常:
C:\Users\54353\AppData\Local\Programs\Python\Python36\python.exe "C:/Users/54353/PycharmProjects/untitled/爬蟲/圖片 - 某網站.py" Traceback (most recent call last): File "C:/Users/54353/PycharmProjects/untitled/爬蟲/圖片 - 某網站.py", line 100, in <module> ip = set_IPlsit2() File "C:/Users/54353/PycharmProjects/untitled/爬蟲/圖片 - 某網站.py", line 95, in set_IPlsit2 response = ure.urlopen(url) File "C:\Users\54353\AppData\Local\Programs\Python\Python36\lib\urllib\request.py", line 223, in urlopen return opener.open(url, data, timeout) File "C:\Users\54353\AppData\Local\Programs\Python\Python36\lib\urllib\request.py", line 532, in open response = meth(req, response) File "C:\Users\54353\AppData\Local\Programs\Python\Python36\lib\urllib\request.py", line 642, in http_response 'http', request, response, code, msg, hdrs) File "C:\Users\54353\AppData\Local\Programs\Python\Python36\lib\urllib\request.py", line 570, in error return self._call_chain(*args) File "C:\Users\54353\AppData\Local\Programs\Python\Python36\lib\urllib\request.py", line 504, in _call_chain result = func(*args) File "C:\Users\54353\AppData\Local\Programs\Python\Python36\lib\urllib\request.py", line 650, in http_error_default raise HTTPError(req.full_url, code, msg, hdrs, fp) urllib.error.HTTPError: HTTP Error 403: Forbidden Process finished with exit code 1
分析：
出現上面的異常是因為用 urllib.request.urlopen 方式打開一個URL，服務器端只會收到一個單純的對於該頁面訪問的請求，但是服務器並不知道發送這個請求使用的瀏覽器，操作系統，硬件平台等信息，而缺失這些信息的請求往往都是非正常的訪問，例如爬蟲。
有些網站為了防止這種非正常的訪問，會驗證請求信息中的UserAgent，如果UserAgent存在異常或者是不存在,那么這次請求將會被拒絕。
解決方法：
在請求中添加UserAgent,代碼如下
1 headers = {'User-Agent':'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:23.0) Gecko/20100101 Firefox/23.0'} 2 req = urllib.request.Request(url=chaper_url, headers=headers) 3 urllib.request.urlopen(req).read()