Python如何使用队列方式实现多线程爬虫

说明：糗事百科段子的爬取，采用了队列和多线程的方式，其中关键点是Queue.task_done()、Queue.join()，保证了线程的有序进行。

代码如下

import requestsfrom lxml import etreeimport jsonfrom queue import Queueimport threadingclass Qsbk(object): def __init__(self): self.headers = { 'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36', 'Referer': 'https://www.qiushibaike.com/' } # 实例化三个队列，用来存放内容 self.url_queue = Queue() self.html_queue = Queue() self.content_queue = Queue() def get_total_url(self): ''' 获取了所有的页面url，并且返回url_list return:url_list 现在放入url_queue队列中保存 ''' url_temp = 'https://www.qiushibaike.com/text/page/{}/' url_list = list() for i in range(1,13): # url_list.append(url_temp.format(i)) # 将生成的url放入url_queue队列 self.url_queue.put(url_temp.format(i)) def parse_url(self): ''' 发送请求，获取响应，同时etree处理html ''' while self.url_queue.not_empty: # 判断非空，为空时结束循环 # 从队列中取出一个url url = self.url_queue.get() print('parsing url:',url) # 发送请求 response = requests.get(url,headers=self.headers,timeout=10) # 获取html字符串 html = response.content.decode() # 获取element类型的html html = etree.HTML(html) # 将生成的element对象放入html_queue队列 self.html_queue.put(html) # Queue.task_done() 在完成一项工作之后，Queue.task_done()函数向任务已经完成的队列发送一个信号 self.url_queue.task_done() def get_content(self): ''' 解析网页内容，获取想要的信息 ''' while self.html_queue.not_empty: items = list() html = self.html_queue.get() total_div = html.xpath('//div[@class=’col1 old-style-col1’]/div') for i in total_div:author_img = i.xpath('.//a[@rel=’nofollow’]/img/@src')author_img = 'https'+author_img[0] if len(author_img)>0 else Noneauthor_name = i.xpath('.//a[@rel=’nofollow’]/img/@alt')author_name = author_name[0] if len(author_name)>0 else Noneauthor_href = i.xpath('./a/@href')author_href = 'https://www.qiushibaike.com/'+author_href[0] if len(author_href)>0 else Noneauthor_gender = i.xpath('./div[1]/div/@class')author_gender = author_gender[0].split(' ')[-1].replace('Icon','').strip() if len(author_gender)>0 else Noneauthor_age = i.xpath('./div[1]/div/text()')author_age = author_age[0] if len(author_age)>0 else Nonecontent = i.xpath('./a/div/span/text()')content = content[0].strip() if len(content)>0 else Nonecontent_vote = i.xpath('./div[@class=’stats’]/span[@class=’stats-vote’]/i/text()')content_vote = content_vote[0] if len(content_vote)>0 else Nonecontent_comment_numbers = i.xpath('./div[@class=’stats’]/span[@class=’stats-comments’]/a/i/text()')content_comment_numbers = content_comment_numbers[0] if len(content_comment_numbers)>0 else Noneitem = { 'author_name':author_name, 'author_age' :author_age, 'author_gender':author_gender, 'author_img':author_img, 'author_href':author_href, 'content':content, 'content_vote':content_vote, 'content_comment_numbers':content_comment_numbers,}items.append(item) self.content_queue.put(items) # task_done的时候，队列计数减一 self.html_queue.task_done() def save_items(self): ''' 保存items ''' while self.content_queue.not_empty: items = self.content_queue.get() with open('quishibaike.txt',’a’,encoding=’utf-8’) as f:for i in items: json.dump(i,f,ensure_ascii=False,indent=2) self.content_queue.task_done() def run(self): # 获取url list thread_list = list() thread_url = threading.Thread(target=self.get_total_url) thread_list.append(thread_url) # 发送网络请求 for i in range(10): thread_parse = threading.Thread(target=self.parse_url) thread_list.append(thread_parse) # 提取数据 thread_get_content = threading.Thread(target=self.get_content) thread_list.append(thread_get_content) # 保存 thread_save = threading.Thread(target=self.save_items) thread_list.append(thread_save) for t in thread_list: # 为每个进程设置为后台进程，效果是主进程退出子进程也会退出 t.setDaemon(True) t.start()# 让主线程等待，所有的队列为空的时候才能退出 self.url_queue.join() self.html_queue.join() self.content_queue.join()if __name__=='__main__': obj = Qsbk() obj.run()

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