爬取页面的封装函数2

from urllib import request,parse
from urllib.error import HTTPError,URLError

#保存cookie
from http import cookiejar

class session(object):
    def __init__(self):
        cookie_object = cookiejar.CookieJar()
        #handler 对应着一个操作
        handler = request.HTTPCookieProcessor(cookie_object)
        #opener 遇到有cookie的response的时候
        #调用handler内部的一个函数，存储到cookie object
        self.opener = request.build_opener(handler)
 
    def get(self,url,headers = None):
        
        return get(url,headers,self.opener)
    
    def post(self,url,form,headers = None):
    
        return post(url,form,headers,self.opener)

def get(url,header = None,opener = None):

    return urlrequests(url,headers,self.opener)

def post(self,url,form,headers = None):

    return urlrequests(url,form,headers = headers,opener = opener)

def urlrequests(url,form = None,headers = None,opener = None):
    
    user_agent = 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36'
    
    #如果用户需要自行传入headers，则覆盖之前的headers
    if headers == None:
        headers = {
            'User-Agent': user_agent
        }
    html_bytes = b''
    
    try:
        if form:
            #post
            #转换成str
            form_str = parse.urlencode(form,encoding = 'utf-8')
            #转换成bytes
            form_bytes = form_str.encode('utf-8')
            req = request.Request(url,data = form_bytes,headers = headers)
        else:
            #get
            req = request.Request(url,headers = headers)
        
        if opener:
            response = opener.open(req)
        else:
            response = request.urlopen(req)
        html_bytes = response.read()
    
    except HTTPError as e:
        print(e)

    except URLError as e:
        print(e)
    
    return html_bytes

if __name__ == '__main__':
    
    url = 'http://www.baidu.com'
    html_byte = get(url)
    print(html_byte)