多线程糗事百科案例

案例要求参考上一个糗事百科单进程案例

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()

多线程示意图

# coding=utf-8
import requests
from lxml import etree
import json
from queue import Queue
import threading

class 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urllist
        return ：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html
            self.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 None
                author_name = i.xpath('./div[@class="author clearfix"]/a[2]/h2/text()')
                author_name = author_name[0] if len(author_name) > 0 else None
                author_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 None
                author_gender = i.xpath('./div[@class="author clearfix"]//div/@class')
                author_gender = author_gender[0].split(" ")[-1].replace("Icon", "") if len(author_gender) > 0 else None
                author_age = i.xpath('./div[@class="author clearfix"]//div/text()')
                author_age = author_age[0] if len(author_age) > 0 else None
                content = 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 None
                content_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 None
                hot_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 None
                hot_comment = i.xpath('./a[@class="indexGodCmt"]/div/div/text()')
                hot_comment = hot_comment[0].replace("\n：", "").replace("\n", "") if len(hot_comment) > 0 else None
                hot_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 None
                item = 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()