I. Introduction

I've been learning Python for a long time. I've heard that Python crawlers are so powerful before. I've just learned here. I wrote a crawler program with the python video of little turtle, which can download simple web pictures.

Two, code

__author__ = "JentZhang"

import urllib.request
import os
import random
import re


def url_open(url):
    '''
    //Open web page
    :param url:
    :return:
    '''
    req = urllib.request.Request(url)
    req.add_header('User-Agent',
                   'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.75 Safari/537.36')

    # Application agent
    '''
    proxyies = ["111.155.116.237:8123","101.236.23.202:8866","122.114.31.177:808"]
    proxy = random.choice(proxyies)
    proxy_support = urllib.request.ProxyHandler({"http": proxy})
    opener = urllib.request.build_opener(proxy_support)
    urllib.request.install_opener(opener)
    '''

    response = urllib.request.urlopen(url)
    html = response.read()

    return html


def save_img(folder, img_addrs):
    '''
    //Save pictures
    :param folder: Folders to save
    :param img_addrs: Picture address (list)
    :return:
    '''
    # Create folders for pictures
    if not os.path.exists(folder):
        os.mkdir(folder)
    os.chdir(folder)
    for each in img_addrs:
        filename = each.split('/')[-1]
        try:
            with open(filename, 'wb') as f:
                img = url_open("http:" + each)
                f.write(img)
        except urllib.error.HTTPError as e:
            # print(e.reason)
            pass
    print('Complete!')


def find_imgs(url):
    '''
    //Get all picture links
    :param url: Connection address
    :return: List of picture addresses
    '''
    html = url_open(url).decode("utf-8")
    img_addrs = re.findall(r'src="(.+?\.gif)', html)
    return img_addrs


def get_page(url):
    '''
    //How many pages of pictures are there currently
    :param url: Web address
    :return:
    '''
    html = url_open(url).decode('utf-8')
    a = html.find("current-comment-page") + 23
    b = html.find("]</span>", a)

    return html[a:b]


def download_mm(url="http://jandan.net/ooxx/", folder="OOXX", pages=1):
    '''
    //Main program (download picture)
    :param folder:Default folder
    :param pages: Pages downloaded
    :return:
    '''
    page_num = int(get_page(url))

    for i in range(pages):
        page_num -= i
        page_url = url + "page-" + str(page_num) + "#comments"
        img_addrs = find_imgs(page_url)
        save_img(folder, img_addrs)


if __name__ == "__main__":
    download_mm()

Three, summary

Because of the code access to the URL has used the anti crawler algorithm. so I can't get the picture I want. so, take a note of a reptile. It's just for learning reference....

Finally: I can change the jpg format to gif and climb to a poor gif image:

The first is a picture placeholder for the anti crawler mechanism, nothing at all