一、requests庫的使用入門
requests.request() 構(gòu)造一個請求忆谓，支撐以下各方法
requests.get() 獲取HTML網(wǎng)頁的主要方法舰始，對應(yīng)于HTTP的GRT
requests.head() 獲取HTML網(wǎng)頁頭信息
requests.post() 對應(yīng)于HTTP的POST
requests.put() 對應(yīng)于HTTP的PUT
requests.patch() 向HTML提交局部修改請求
requests.delete() 向HTML提交刪除請求
二闸衫、ROBOTS協(xié)議
爬蟲可能被網(wǎng)站拒絕 需要修改Header
爬蟲時注意\robots.txt
三屹蚊、BeautifulSoup
屬性： Tag、Name坝辫、Attributes篷就、NavigableString、Comment
遍歷：
平行遍歷: .contents .children .descendants
上行遍歷: .parent .parents
下行遍歷: .next_sibling .next_siblings .previous_sibling .previous_siblings
個別函數(shù)：
HTML文本格式化： .prettify()
查找函數(shù)： .find_all()
四近忙、實例-----大學(xué)排名
import requests
from bs4 import BeautifulSoup
import bs4
def getHTMLText(url):
try:
r = requests.get(url, timeout = 30)
r.raise_for_status()
r.encoding = r.apparent_encoding
return r.text
except:
print("failed")
return ""
def fillUnivList(ulist, html):
soup = BeautifulSoup(html, "html.parser")
for tr in soup.find('tbody').children:
if isinstance(tr, bs4.element.Tag):
tds = tr('td')
ulist.append([tds[0].string, tds[1].string, tds[2].string])
def printUnivList(ulist, num):
print("{:^10}\t{:^6}\t{:^10}".format("排名", "學(xué)校名稱", "得分"))
for i in range(num):
u = ulist[i]
print("{:^10}\t{:^6}\t{:^10}".format(u[0], u[1], u[2]))
def main():
uinfo = []
url = "http://www.zuihaodaxue.com/zuihaodaxuepaiming2016.html"
html = getHTMLText(url)
fillUnivList(uinfo,html)
printUnivList(uinfo,20) #20
