Python 仅获取响应头, 不获取实体的实例

Python  /  管理员 发布于 7年前   196

Python Just get Response Headers, not get content.

1. Use HEAD method

>>> import requests>>> res = requests.head("http://www.baidu.com/")>>> req.head("https://www.baidu.com/").headers{'Content-Encoding': 'gzip', 'Server': 'bfe/1.0.8.18', 'Last-Modified': 'Mon, 13 Jun 2016 02:50:08 GMT', 'Connection': 'Keep-Alive', 'Pragma': 'no-cache', 'Cache-Control': 'private, no-cache, no-store, proxy-revalidate, no-transform', 'Date': 'Fri, 13 Oct 2017 04:36:20 GMT', 'Content-Type': 'text/html'}>>> res.okTrue>>> res.content''# 但是会遇到一些问题, 比如, 服务器不支持 HEAD, 或者拒绝 HEAD.# 如下情况就被拒绝#>>> res = req.head("https://www.douban.com/subject/1/")>>> res<Response [403]>>>> res.okFalse>>> res.content''>>> res.headers{'Content-Encoding': 'gzip', 'Keep-Alive': 'timeout=30', 'Server': 'dae', 'Connection': 'keep-alive', 'Date': 'Fri, 13 Oct 2017 04:39:00 GMT', 'Content-Type': 'text/html'}

不是很通用, 因为有些服务器不支持.

2. Use urllib

import urllib>>> res = urllib.urlopen("http://127.0.0.1:8000/git.exe")>>> res.url'http://127.0.0.1:8000/git.exe'>>> res.headers.headers['Server: SimpleHTTP/0.6 Python/2.7.10\r\n', 'Date: Fri, 13 Oct 2017 06:06:37 GMT\r\n', 'Content-type: application/x-msdownload\r\n', 'Content-Length: 7569408\r\n', 'Last-Modified: Fri, 16 Dec 2016 07:09:32 GMT\r\n']>>> len(r.read())7569408# urllib 只有在调用 read/readline/readlines 的时候才会从 web 服务器读取数据.# 源码可以在 urllib/httplib 中找到. # urllib.pydef urlopen(url, ...): opener = FancyURLopener() return opener.open(url)class FancyURLopener(URLopener).open(): getattr(self, name)(url)class URLopener.open_http(): errcode, errmsg, headers = h.getreply() if(200 <= errcode < 300):  return addinfourl(fp, headers, "http:" + url, errcode) else:  if data is None:   return self.http_error(url, fp, errcode, errmsg, headers)  else:   return self.http_error(url, fp, errcode, errmsg, headers, data)class URLopener.http_error(): return method(url, fp, errcode, errmsg, headers)class FancyURLopener.http_error_default(): return addinfourl(fp, headers, "http:" + url, errcode)class addinfourl(addbase): # 代码中并没有对 fp 做任何操作,包括读写. class addbase.__init __(): self.fp = fp self.read = self.fp.read self.readline = self.fp.readline if hasattr(self.fp, "readlines"): self.readlines = self.fp.readlines  self.fileno = self.fp.fileno # ... ...

可以看到, urllib.open 最终返回了 addbase, addbase 中没有对 socket 做任务处理, 不会有任何读写. 之后显示调用 read/readline/readlines, 才会从 web 服务器读取数据.

图 1. 初始化网络.

图 2. urlopen() 之后

图 3. read() 之后

3. Use socket

看过 urllib 之后, 可以使用 socket 写一个方法, 只获取 header.

import socketimport ssl_timeout = 10socket.setdefaulttimeout(_timeout)def get_header(host, port=80, uri="/", method="GET", user_ssl=False): # 这里可以再扩充一下, 支持 headers conn = None header = """%s %s HTTP/1.1\r\nHost: %s\r\nConnection: close\r\nUser-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36\r\n\r\n""" % (  method, uri, host) if user_ssl:  ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)  _socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  conn = ssl_context.wrap_socket(_socket, server_hostname=host)  conn.connect((host, port))  conn.send(header) else:  conn = socket.create_connection((host, port), _timeout)  conn.sendall(header) text = "" while True:  if "\r\n\r\n" in text:   break  buff = conn.recv(10)  text += buff  # print buff conn.close() return text.split("\r\n\r\n")[0]if __name__ == '__main__': print get_header("www.douban.com", uri="/subject/27076001/") print print get_header("www.douban.com", uri="/subject/27076001/", port=443, user_ssl=True)

➜ 76[14:48:20]zhipeng@zhipeng-MacBook ~/demo/python�� $ python test_header.pyHTTP/1.1 301 Moved PermanentlyDate: Fri, 13 Oct 2017 06:48:23 GMTContent-Type: text/htmlContent-Length: 178Connection: closeLocation: https://www.douban.com/subject/27076001/Server: daeHTTP/1.1 302 Moved TemporarilyServer: ADSSERVER/45863Date: Fri, 13 Oct 2017 06:48:23 GMTContent-Type: text/htmlTransfer-Encoding: chunkedConnection: closeLocation: https://sec.douban.com/b?r=https%3A%2F%2Fwww.douban.com%2Fsubject%2F27076001%2FStrict-Transport-Security: max-age=15552000;Set-Cookie: __ads_session=uY8l3pLW/AjCKJ8Y4wA=; domain=.douban.com; path=/X-Powered-By-ADS: uni-jnads-1-02➜ 77[14:48:23]zhipeng@zhipeng-MacBook ~/demo/python �� $ 

参考

<< Python socket server handle HTTPS request >> (https://stackoverflow.com/questions/32062925/python-socket-server-handle-https-request)

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