【发布时间】:2018-11-04 06:25:31
【问题描述】:
我正在尝试从网页中提取一些信息,我有以下代码:
import re
from math import ceil
from urllib.request import urlopen as uReq, Request
from bs4 import BeautifulSoup as soup
InitUrl="https://mtgsingles.gr/search?q="
NumOfCrawledPages = 0
URL_Next = ""
NumOfPages=5
for i in range(0, NumOfPages):
if i == 0:
Url = InitUrl
else:
Url = URL_Next
UClient = uReq(Url) # downloading the url
page_html = UClient.read()
UClient.close()
page_soup = soup(page_html, "html.parser")
cards = page_soup.findAll("div", {"class": ["iso-item", "item-row-view"]})
for card in cards:
card_name = card.div.div.strong.span.contents[3].contents[0].replace("\xa0 ", "")
if len(card.div.contents) > 3:
cardP_T = card.div.contents[3].contents[1].text.replace("\n", "").strip()
else:
cardP_T = "Does not exist"
cardType = card.contents[3].text
print(card_name + "\n" + cardP_T + "\n" + cardType + "\n")
try:
URL_Next = "https://mtgsingles.gr" + page_soup.findAll("li", {"class": "next"})[0].contents[0].get("href")
print("The next URL is: " + URL_Next + "\n")
except IndexError:
print("Crawling process completed! No more infomation to retrieve!")
else:
print("The next URL is: " + URL_Next + "\n")
NumOfCrawledPages += 1
Url= URL_Next
finally:
print("Moving to page : " + str(NumOfCrawledPages + 1) + "\n")
代码运行良好,没有出现错误,但结果不如预期。我正在尝试从页面中提取一些信息以及下一页的 url。最终我希望程序运行 5 次并爬取 5 页。但是此代码对给定的初始页面 (InitUrl="xyz.com") 进行了 5 次抓取,并且不会在提取的下一页 url 中继续进行。我尝试通过输入一些打印语句来调试它,以查看问题出在哪里,我认为问题出在这些语句上:
UClient = uReq(Url)
page_html = UClient.read()
UClient.close()
由于某种原因 urlopen 在 for 循环中不能重复工作。为什么会这样?在for语句中使用urlopen有错吗?
【问题讨论】:
标签: python-3.x web-crawler urlopen