pip install requestsOr download it directly from her og installere manuelt.
Laster ned filer
Python3# imported the requests library import requests image_url = 'https://www.python.org/static/community_logos/python-logo-master-v3-TM.webp' # URL of the image to be downloaded is defined as image_url r = requests.get(image_url) # create HTTP response object # send a HTTP request to the server and save # the HTTP response in a response object called r with open('python_logo.webp''wb') as f: # Saving received content as a png file in # binary format # write the contents of the response (r.content) # to a new file in binary mode. f.write(r.content)
This small piece of code written above will download the following image from the web. Now check your local directory(the folder where this script resides) and you will find this image: All we need is the URL of the image source. (You can get the URL of image source by right-clicking on the image and selecting the View Image option.) Last ned store filer
HTTP-responsinnholdet ( r.innhold ) er ikke annet enn en streng som lagrer fildataene. Så det vil ikke være mulig å lagre alle dataene i en enkelt streng i tilfelle store filer. For å løse dette problemet gjør vi noen endringer i programmet vårt:r = requests.get(URL stream = True)Setting strøm parameter til ekte vil kun føre til nedlasting av svarhoder og tilkoblingen forblir åpen. Dette unngår å lese innholdet på en gang i minnet for store svar. En fast del vil bli lastet inn hver gang mens r.iter_content is iterated. Here is an example: Python3
import requests file_url = 'http://codex.cs.yale.edu/avi/db-book/db4/slide-dir/ch1-2.pdf' r = requests.get(file_url stream = True) with open('python.pdf''wb') as pdf: for chunk in r.iter_content(chunk_size=1024): # writing one chunk at a time to pdf file if chunk: pdf.write(chunk)
Laster ned videoer
I dette eksemplet er vi interessert i å laste ned alle videoforelesningene som er tilgjengelige om dette web-side . Alle arkivene til dette foredraget er tilgjengelige her . So we first scrape the webpage to extract all video links and then download the videos one by one. Python3
import requests from bs4 import BeautifulSoup ''' URL of the archive web-page which provides link to all video lectures. It would have been tiring to download each video manually. In this example we first crawl the webpage to extract all the links and then download videos. ''' # specify the URL of the archive here archive_url = 'https://public.websites.umich.edu/errors/404.html def get_video_links(): # create response object r = requests.get(archive_url) # create beautiful-soup object soup = BeautifulSoup(r.content'html5lib') # find all links on web-page links = soup.findAll('a') # filter the link sending with .mp4 video_links = [archive_url + link['href'] for link in links if link['href'].endswith('mp4')] return video_links def download_video_series(video_links): for link in video_links: '''iterate through all links in video_links and download them one by one''' # obtain filename by splitting url and getting # last string file_name = link.split('/')[-1] print( 'Downloading file:%s'%file_name) # create response object r = requests.get(link stream = True) # download started with open(file_name 'wb') as f: for chunk in r.iter_content(chunk_size = 1024*1024): if chunk: f.write(chunk) print( '%s downloaded!n'%file_name ) print ('All videos downloaded!') return if __name__ == '__main__': # getting all video links video_links = get_video_links() # download all videos download_video_series(video_links)
Advantages of using Requests library to download web files are: - Man kan enkelt laste ned nettkatalogene ved å iterere rekursivt gjennom nettsiden!
- Dette er en nettleseruavhengig metode og mye raskere!
- Man kan ganske enkelt skrape en nettside for å få alle fil-URLene på en nettside og dermed laste ned alle filene i en enkelt kommando-
Implementering av nettskraping i Python med BeautifulSoup