16-多线程爬取糗事百科（python+Tread）

https://www.cnblogs.com/alamZ/p/7414020.html   课件内容

#_*_ coding: utf-8 _*_
'''
Created on 2018年7月17日
@author: sss
function: 利用多线程爬取糗事百科页面

'''
#使用线程库
import threading
#队列
from queue import Queue
#解析库
from lxml import etree
#json处理
import json
import time 
import requests
from pickle import FALSE

CRAWL_EXIT = False
PARSE_EXIT = False 

class TreadCrawl(threading.Thread):
    def __init__(self, threadName, pageQueue, dataQueue):
        #threading.Thread.__init__(self)
        #掉用父类初始化方法
        super(TreadCrawl, self).__init__()
        #线程名
        self.threadName = threadName
        #页码队列
        self.pageQueue = pageQueue
        #数据队列
        self.dataQueue = dataQueue
        #请求报头
        self.headers = {"User-Agent" : "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;"}
        
    def run(self):
        print('启动' + self.threadName)
        while not CRAWL_EXIT:
            try:
                #取出一个数字，先进先出
                #课选参数block,默认值为True
                #1.如果对列为空，block为True的话，不会结束，会进入阻塞转态，直到队列有新的数据
                #2.如果队列为空，block为false的话，就弹出一个Queue.empty（）异常
                page = self.pageQueue.get(False)
                url = "http://www.qiushibaike.com/8hr/page/" + str(page) +"/"
                content = requests.get(url, headers = self.headers).text
                time.sleep(1)
                self.dataQueue.put(content)
            except:
                pass
        print('结束' + self.threadName)    

class ThreadParse(threading.Thread):
    def __init__(self, threadName, dataQueue, filename, lock):
#         print('parse')
        super(ThreadParse, self).__init__()
        #线程名
        self.threadName = threadName
        #数据队列
        self.dataQueue = dataQueue
        #保存解析后数据的文件名
        self.filename = filename 
        #锁
        self.lock = lock
    
    def run(self):
        print('启动' + self.threadName)
        while not PARSE_EXIT:
            try:
                html = self.dataQueue.get(False)
#                 print('0000000000000000000')
                self.parse(html)
            except:
                pass
        print('退出' + self.threadName)
    
    def parse(self, html):
        #解析为HTML DOM
        html = etree.HTML(html)
        
        node_list = html.xpath('//div[contains(@id, "qiushi_tag_")]')
#         print(node_list)
#         print('6666666666666')
        items = {}
        for node in node_list:
            #用户名
        #     username = node.xpath('./div/a/h2')[0].text
            username = node.xpath('.//h2')[0].text.replace('
','')   #用replace去掉

            #图片连接
            image = node.xpath('.//img/@src')#[0]
            #取出标题下的内容
            content = node.xpath('./a/div/span')[0].text.replace('
','')
            #点赞
            zan = node.xpath('./div/span/i')[0].text
            #评论
            comment = node.xpath('./div/span/a/i')[0].text
            
            items = {
                'username' : username,
                'image' : image,
                'content' : content,
                'zan' : zan,
                'comments' : comment
                }                  
            
            # with 后面有两个必须执行的操作：__enter__ 和 __exit__
            # 不管里面的操作结果如何，都会执行打开、关闭
            # 打开锁、处理内容、释放锁
            with self.lock:
                # 写入存储的解析后的数据
                self.filename.write(json.dumps(items, ensure_ascii = False) + "
")
        print('已写入')    
            

def main():
    #页码队列，表示20个页面
    pageQueue = Queue(20)
    #放入1~20的数字，先进先出
    for i in range(1, 5):
        pageQueue.put(i)
        
    #采集的结果（每页的html原码）的数据队列，参数为空表示不限制
    dataQueue = Queue()
    
    #打开文件
    filename = open('./qiushi/duanzi.json', 'a', encoding='utf-8')

    #创建锁：
    lock = threading.Lock()
    
    #三个采集的名字
    crawlList = ['采集线程 1号','采集线程 2号','采集线程 3号']
    
    #存储三个采集线程的列表集合
    threadcrawl = []
    for threadName in crawlList:
        thread = TreadCrawl(threadName, pageQueue, dataQueue)
        thread.start()
        threadcrawl.append(thread)
        
    #三个解析线程的名字
    parseList = ['解析线程1号', '解析线程2号', '解析线程3号']
    #存储三个解析线程
    threadparse = []
    for threadName in parseList:
        thread = ThreadParse(threadName, dataQueue, filename, lock)
        thread.start()
        threadparse.append(thread)
    
    #等待pageQueue队列为空，也就是等待之前的操作执行完毕，
    while not pageQueue.empty():
        pass
    
    #如果pageQueue为空，采集线程退出循环
    global CRAWL_EXIT
    CRAWL_EXIT = True
    
    print('pageQueue为空')
    
    for thread in threadcrawl:
        thread.join()
        print(1)
        
    while not dataQueue.empty():
        pass
        
    global PARSE_EXIT
    PARSE_EXIT = True
    
    for thread in threadparse:
        thread.join()
        print('2')
    
    with lock:
        #关闭文件
        filename.close()
    print('谢谢使用！')

if __name__ == "__main__":
    main()