一. Queue（队列对象）

Queue是python中的标准库，可以直接import Queue引用;队列是线程间最常用的交换数据的形式

python下多线程的思考

对于资源，加锁是个重要的环节。因为python原生的list,dict等，都是not thread safe的。而Queue，是线程安全的，因此在满足使用条件下，建议使用队列

1. 初始化： class Queue.Queue(maxsize) FIFO 先进先出

2. 包中的常用方法:
   Queue.qsize() 返回队列的大小
   Queue.empty() 如果队列为空，返回True,反之False
   Queue.full() 如果队列满了，返回True,反之False
   Queue.full 与 maxsize 大小对应
   Queue.get([block[, timeout]])获取队列，timeout等待时间

3. 创建一个“队列”对象
   import queue
   myqueue = queue.Queue(maxsize = 10)

4. 将一个值放入队列中
   myqueue.put(10)

5. 将一个值从队列中取出

myqueue.get()

二. 多线程示意图

三. 代码示例

# coding=utf-8
import requests
from lxml import etree
import json
from queue import Queue
import threadingclass Qiubai:def __init__(self):self.headers = {"User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWeb\Kit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36"}self.url_queue = Queue()   #实例化三个队列，用来存放内容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urllistreturn ：list'''url_temp = 'https://www.qiushibaike.com/8hr/page/{}/'# url_list = []for i in range(1,36):# url_list.append(url_temp.format(i))self.url_queue.put(url_temp.format(i))def parse_url(self):'''一个发送请求，获取响应，同时etree处理html'''while self.url_queue.not_empty:url = self.url_queue.get()print("parsing url:",url)response = requests.get(url,headers=self.headers,timeout=10) #发送请求html = response.content.decode() #获取html字符串html = etree.HTML(html) #获取element 类型的htmlself.html_queue.put(html)self.url_queue.task_done()def get_content(self):''':param url::return: 一个list，包含一个url对应页面的所有段子的所有内容的列表'''while self.html_queue.not_empty:html = self.html_queue.get()total_div = html.xpath('//div[@class="article block untagged mb15"]') #返回divelememtn的一个列表items = []for i in total_div: #遍历div标枪，获取糗事百科每条的内容的全部信息author_img = i.xpath('./div[@class="author clearfix"]/a[1]/img/@src')author_img = "https:" + author_img[0] if len(author_img) > 0 else Noneauthor_name = i.xpath('./div[@class="author clearfix"]/a[2]/h2/text()')author_name = author_name[0] if len(author_name) > 0 else Noneauthor_href = i.xpath('./div[@class="author clearfix"]/a[1]/@href')author_href = "https://www.qiushibaike.com" + author_href[0] if len(author_href) > 0 else Noneauthor_gender = i.xpath('./div[@class="author clearfix"]//div/@class')author_gender = author_gender[0].split(" ")[-1].replace("Icon", "") if len(author_gender) > 0 else Noneauthor_age = i.xpath('./div[@class="author clearfix"]//div/text()')author_age = author_age[0] if len(author_age) > 0 else Nonecontent = i.xpath('./a[@class="contentHerf"]/div/span/text()')content_vote = i.xpath('./div[@class="stats"]/span[1]/i/text()')content_vote = content_vote[0] if len(content_vote) > 0 else Nonecontent_comment_numbers = i.xpath('./div[@class="stats"]/span[2]/a/i/text()')content_comment_numbers = content_comment_numbers[0] if len(content_comment_numbers) > 0 else Nonehot_comment_author = i.xpath('./a[@class="indexGodCmt"]/div/span[last()]/text()')hot_comment_author = hot_comment_author[0] if len(hot_comment_author) > 0 else Nonehot_comment = i.xpath('./a[@class="indexGodCmt"]/div/div/text()')hot_comment = hot_comment[0].replace("\n：", "").replace("\n", "") if len(hot_comment) > 0 else Nonehot_comment_like_num = i.xpath('./a[@class="indexGodCmt"]/div/div/div/text()')hot_comment_like_num = hot_comment_like_num[-1].replace("\n", "") if len(hot_comment_like_num) > 0 else Noneitem = dict(author_name=author_name,author_img=author_img,author_href=author_href,author_gender=author_gender,author_age=author_age,content=content,content_vote=content_vote,content_comment_numbers=content_comment_numbers,hot_comment=hot_comment,hot_comment_author=hot_comment_author,hot_comment_like_num=hot_comment_like_num)items.append(item)self.content_queue.put(items)self.html_queue.task_done()  #task_done的时候，队列计数减一def save_items(self):'''保存items:param items:列表'''while self.content_queue.not_empty:items = self.content_queue.get()f = open("qiubai.txt","a")for i in items:json.dump(i,f,ensure_ascii=False,indent=2)# f.write(json.dumps(i))f.close()self.content_queue.task_done()def run(self):# 1.获取url list# url_list = self.get_total_url()thread_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:t.setDaemon(True)  #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.start()          #为了解决程序结束无法退出的问题## for t in thread_list:#     t.join()self.url_queue.join()   #让主线程等待，所有的队列为空的时候才能退出self.html_queue.join()self.content_queue.join()if __name__ == "__main__":qiubai = Qiubai()qiubai.run()