python web crawler tutorial

constructed in Scrapy is as followsTestspider (Crawlspider):Name="Test1"allowd_domains=[' http://www.xunsee.com '] start_urls=["http://www.xunsee.com/article/8c39f5a0-ca54-44d7-86cc-148eee4d6615/1.shtml"]Rules= (Rule (Linkextractor (allow= (' \d\.shtml ')), callback=' Parse_item ', Follow=true),)PrintRulesdefParse_item (self, Response): PrintResponse.urlSel=selector (response)context="'Content=sel.xpath ('//div[@id = ' content_1 ']/text () '). Extract () forCinchContentContext=context+c.enco

Here are a few things to do before crawling a Web site1. Download and check the Web site's robots.txt file to let the crawler know what restrictions the site crawls.2. Check site Map3. Estimating Site Sizeuse Baidu or Google search Site:example.webscraping.comThe results are as followsFind related results in about 5The number is the estimated value. Site administ

://10.106.0.217:8080/opac_two/reader/infoList.jsp ', data = postdata) #访问该链接 # #result = Opener.open (req) result = Urllib2.urlopen (req) #打印返回的内容 #print result.read (). Decode (' GBK '). Encode (' Utf-8 ') #打印cookie的值for item in Cookie:print ' cookie:name = ' +item.name priNT ' Cookie:value = ' +item.valueresult = Opener.open (' http://10.106.0.217:8080/opac_two/top/top.jsp ') print U ""------ ------------------------------------------------------------------------"" "MyPage = Result.read () my

The difficulties encountered:1. python3.6 installation, it is necessary to remove the previous completely clean, the default installation directory is: C:\Users\ song \appdata\local\programs\python2. Configuration variables There are two Python versions in the PATH environment variable, environment variables: add C:\Users\ song \appdata\local\programs\python\python36-32 in PathThen PIP configuration: Path i

, and save the cookie to the variableresult = Opener.open (loginurl,postdata)#保存cookie到cookie. txtCookie.save (ignore_discard=true, ignore_expires=true)#利用cookie请求访问另一个网址, this URL is the score query URLgradeurl = ' Http://jwxt.sdu.edu.cn:7890/pls/wwwbks/bkscjcx.curscopre '#请求访问成绩查询网址result = Opener.open (Gradeurl)print result.read ()the principle of the above procedure is as followscreate a opener with a cookie, save the logged-in cookie when accessing the URL of the login, and then use this co

1, Python web crawler to get Taobao commodity price code: #-*-coding:utf-8-*-' Created on March 17, 2017 @author: Lavi ' "Import requests from BS4 import BeautifulSoup import BS4 I Mport re def gethtmltext (URL): try:r = Requests.get (url,timeout=30) r.raise_for_status R.enco Ding = r.apparent_encoding return r.text except:return "" Def Parserpage (goodslist,htm

Python-written web crawler (very simple)This is one of my classmates passed to me a small web crawler, feel very interesting, and share with you. However, there is a point to note, to use python2.3, if the use of python3.4 will be some problems arise.The

=============== crawler principle ==================Access the website via python, get the HTML code of the website, and get the image address of SRC in the specific IMG tag via regular expression.Then access the image address and save the picture locally via IO.=============== script code ==================ImportUrllib.request#Network access ModuleImportRandom#random number Generation moduleImportRe#Regula

the Python parser by default, the file is recognized as ASCII encoded format, Chinese of course, do not mistake. The solution to this problem is to explicitly inform the parser of the encoding format of our files. #!/usr/bin/env python#-*-Coding=utf-8-*- That's all you can do. (2) Installation xlwt3 is not successful.Download XLWT3 from the web for installation

. The engine gets the first URL to crawl from the spider, and then dispatches it as a request in the schedule. The engine gets the page that crawls next from the dispatch. The schedule returns the next crawled URL to the engine, which the engine sends to the downloader via the download middleware. When the Web page is downloaded by the downloader, the response content is sent to the engine via the download middleware. The engine re

text,flag initial value is False __init__(self):Htmlparser. __init__(self)Self. flag=FalseSelf. text=[]Handle_starttag implemented as long as Tag=span, then set flag to true Handle_starttag (self, tag,attrs):' span ' :self. Flag=true Handle_data is implemented as long as flag=true extracts the data and saves it in the text list .Handle_data (self, data):SelfTrue:DataSelf. Text.append (data)So when does the data-extracting action end: It depends on the handle_endtag. Similarly , when enco

Python web crawler and information extraction (2) -- BeautifulSoup, BeautifulSoup official introduction: Beautiful Soup is a Python library that can extract data from HTML or XML files. It can implement the usual document navigation, searching, and modifying methods through your favorite converter. Https://www.crummy.

[Python] web crawler (4): Opener, Handler, and openerhandler Before proceeding, let's first explain the two methods in urllib2: info and geturl.The response object response (or HTTPError instance) returned by urlopen has two useful methods: info () and geturl () 1. geturl (): Geturl () returns the obtained real URL, which is useful because urlopen (or the opener

The code and tools usedSample site source + Framework + book pdf+ Chapter codeLink: https://pan.baidu.com/s/1miHjIYk Password: af35Environmentpython2.7Win7x64Sample Site SetupWswp-places.zip in the book site source codeFrames used by the Web2py_src.zip site1 Decompression Web2py_src.zip2 then go to the Web2py/applications directory3 Extract the Wswp-places.zip to the applications directory4 return to the previous level directory, to the Web2py directory, double-click web2py.py, or execute comman

Python Crawler Tutorial -09-error moduleToday's protagonist is the error, crawl, it is easy to appear wrong, so we have to do in the code, common mistakes in the place, about Urllib.errorUrlerror Reasons for Urlerror production: 1. No network connection 2. Server Connection failure 3. The specified server could not be found 4

Course ObjectivesGetting Started with Python writing web crawlersApplicable peopleData 0 basic enthusiast, career newcomer, university studentCourse Introduction1. Basic HTTP request and authentication method analysis2.Python for processing HTML-formatted data BeautifulSoup module3.Pyhton requests module use and achieve crawl B station, NetEase Cloud, Weibo, conn

(URL, timeout=+) r.raise_for_status () r.encoding = r.apparent_encoding return r.text except: 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[3].string]) def printunivlist (ulist, num): tplt = "{0:^10}\t{1:{3}^10}\t{2:^10}" print(tplt. Format("Rank"

= urllib.request.HTTPCookieProcessor(cookie)opener = urllib.request.build_opener(handler)response = opener.open('http://www.baidu.com')print(response.read().decode('utf-8')Urllib Handling ExceptionsIn the run program to get data, if the program encountered errors in the middle of the time we did not write exception processing, as far as possible to run the data lost; in obtaining the Watercress movie top250, some of the movie parameters are incomplete, causing the

I did not think Python is so powerful, fascinating, previously saw the picture is always a copy and paste, now good, learn Python can use the program will be a picture, save it.Today, I see a lot of beautiful pictures, but the picture a bit more, do not want to a copy and paste, how to do? There is always a way, even if there is no we can create a way.Here's a look at the program I wrote today:#Coding=utf-8

An overviewReference http://www.cnblogs.com/abelsu/p/4540711.html got a python capture of a single Web page, but Python has been upgraded to an all-in-one version. The reference has been invalidated and is largely unused. Modified the next, re-implement the web image capture.Two codes　　#Coding=utf-8#The urllib module p