python 爬虫 循环分页

import os
from time import sleep

import faker
import requests
from lxml import etree

fake = faker.Faker()

base_url = "http://angelimg.spbeen.com"

def get_next_link(url):
    content = downloadHtml(url)
    html = etree.HTML(content)
    next_url = html.xpath("//a[@class='ch next']/@href")
    if next_url:
        return base_url + next_url[0]
    else:
        return False

def downloadHtml(ur):
    user_agent = fake.user_agent()
    headers = {'User-Agent': user_agent,"Referer":"http://angelimg.spbeen.com/"}
    response = requests.get(url, headers=headers,timeout=20)
    if response.status_code != 200:
        return None
    else:
        return response.text

def getImgUrl(content):
    html  = etree.HTML(content)
    img_url = html.xpath('//*[@id="content"]/a/img/@src')
    title = html.xpath(".//div['@class=article']/h2/text()")

    return img_url[0],title[0]

def saveImg(title,img_url):
    if img_url is not None and title is not None:

        title = title.split('【')[0]
        file_path = 'isssss/{}/'.format(title)
        if not os.path.exists(file_path):
            os.makedirs(file_path)
        file_name = img_url.split('/')[-1]

        with open(file_path+file_name+".jpg",'wb') as f:
            user_agent = fake.user_agent()
            headers = {'User-Agent': user_agent,"Referer":"http://angelimg.spbeen.com/"}
            content = requests.get(img_url, headers=headers,timeout=20)
            #request_view(content)
            f.write(content.content)
            print("save img "+ img_url)
            f.close()

def request_view(response):
    import webbrowser
    request_url = response.url
    base_url = '<head><base href="%s">' %(request_url)
    base_url = base_url.encode()
    content = response.content.replace(b"<head>",base_url)
    tem_html = open('tmp.html','wb')
    tem_html.write(content)
    tem_html.close()
    webbrowser.open_new_tab('tmp.html')

def optimizeContent(res):
    res = res.replace('b\'', '')
    res = res.replace('\\n', '')
    res = res.replace('\'', '')
    res = res.replace('style', 'nouse')
    res = res.replace('\.', '')
    return res

def crawl_img(url):
    content = downloadHtml(url)
    if content is not None:
        res = getImgUrl(content)
        title = res[1]
        img_url = res[0]
        title = optimizeContent(title)
        title = title.replace('.', '')
        print(title)
        saveImg(title,img_url)
        return True
    else:
        return None
if __name__ == "__main__":
    try:

        root_url = "http://angelimg.spbeen.com/ang/{}"

        for i in range(37,10000):
            url = root_url.format(i)
            try:
                while url:
                    res = crawl_img(url)
                    if res is None:
                        print(url + ' 无数据')
                        next = i + 1
                        url = root_url.format(next)
                        break
                    else:
                        url = get_next_link(url)
                        print("爬取页面：" + url)
                i = i + 1
            except Exception as e:
                print(str(e))
    except Exception as e:
        print(str(e))

结果