逻辑思路是什么？
1. 获取页面
2. 处理页面，提取信息
3. 格式输出
先走面向过程编程：
1. 要定义3个函数，对应以上三个过程
2. 在__main__函数中传入参数，并执行以上三个过程
#!/usr/bin/python3
import bs4
import requests
from bs4 import BeautifulSoup def getHTMLText(url):
'''获取页面'''
try:
r = requests.get(url, timeout=30)
r.raise_for_status()
r.encoding = r.apparent_encoding
return r.text
except:
return "" def fillUnivList(ulist, html):
'''处理页面'''
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[3].string]) def printUnivList(ulist, num):
'''格式输出页面'''
tplt = "{0:^10}\t{1:{3}^10}\t{2:^10}"
print(tplt.format("排名", "学校名称", "总分", chr(12288)))
for i in range(num):
u = ulist[i]
print(tplt.format(u[0], u[1], u[2], chr(12288))) if __name__ == '__main__':
uinfo = []
url = 'http://www.zuihaodaxue.cn/zuihaodaxuepaiming2016.html'
html = getHTMLText(url)
fillUnivList(uinfo, html)
printUnivList(uinfo, 20) # 输出20个大学排名
如何走向面向对象？
1. 输入： url ？+ 想要获得几条信息？
2. 输出： 格式化信息
3. 对于获取页面和处理页面为私有方法，不应该暴露
#!/usr/bin/python3
import requests
import bs4
from bs4 import BeautifulSoup class SchoolMessage(object):
'''爬取大学排名''' def __init__(self, url, number):
self.url = url
self.number = number def __get_html(self):
'''获得页面'''
try:
r = requests.get(self.url,timeout=30)
r.raise_for_status()
r.encoding = r.apparent_encoding
return r.text
except:
return '1' def __get_message(self):
'''获得信息'''
info = []
html = self.__get_html()
if html is not '1':
soup = BeautifulSoup(html, 'html.parser')
for i in soup.find('tbody').children:
if isinstance(i, bs4.element.Tag):
tds = i('td')
info.append([tds[0].string, tds[1].string, tds[2].string])
return info
else:
return '1' def get_message(self):
'''格式化输出信息'''
info = self.__get_message()
if info is not '1':
temp = "{0:^10}\t{1:{3}^10}\t{2:^10}"
print(temp.format("排名", "学校名称", "总分", chr(12288)))
for i in range(self.number):
u = info[i]
print(temp.format(u[0], u[1], u[2], chr(12288)))
else:
print('爬取失败') if __name__ == '__main__':
url = 'http://www.zuihaodaxue.cn/zuihaodaxuepaiming2016.html'
school_1 = SchoolMessage(url, 10)
school_1.get_message()
所需要的环境：
python 3.5
requests 库
beautifulsoup 库