案例_(多线线程)爬取糗事百科

  1 # 使用了线程库
  2 import threading
  3 # 队列
  4 from queue import Queue
  5 # 解析库
  6 from lxml import etree
  7 # 请求处理
  8 import requests
  9 # json处理
 10 import time
 11 
 12 
 13 class ThreadCrawl(threading.Thread):
 14     def __init__(self, thread_name, page_queue, data_queue):
 15         #threading.Thread.__init__(self)
 16         # 调用父类初始化方法
 17         super(ThreadCrawl, self).__init__()
 18         # 线程名
 19         self.thread_name = thread_name
 20         # 页码队列
 21         self.page_queue = page_queue
 22         # 数据队列
 23         self.data_queue = data_queue
 24         # 请求报头
 25         self.headers = {"User-Agent" : "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;"}
 26 
 27     def run(self):
 28         print("启动 " + self.thread_name)
 29         while not CRAWL_EXIT:
 30             try:
 31                 # 取出一个数字，先进先出
 32                 # 可选参数block，默认值为True
 33                 #1. 如果对列为空，block为True的话，不会结束，会进入阻塞状态，直到队列有新的数据
 34                 #2. 如果队列为空，block为False的话，就弹出一个Queue.empty()异常，
 35                 page = self.page_queue.get(False)
 36                 url = "http://www.qiushibaike.com/8hr/page/" + str(page) +"/"
 37                 #print url
 38                 content = requests.get(url, headers = self.headers).text
 39                 time.sleep(1)
 40                 self.data_queue.put(content)
 41                 #print len(content)
 42             except:
 43                 pass
 44         print("结束 " + self.thread_name)
 45 
 46 class ThreadParse(threading.Thread):
 47     def __init__(self, thread_name, data_queue):
 48         super(ThreadParse, self).__init__()
 49         # 线程名
 50         self.thread_name = thread_name
 51         # 数据队列
 52         self.data_queue = data_queue
 53 
 54     def run(self):
 55         print("启动" + self.thread_name)
 56         while not PARSE_EXIT:
 57             try:
 58                 html = self.data_queue.get(False)
 59                 self.parse(html)
 60             except:
 61                 pass
 62         print("退出" + self.thread_name)
 63 
 64     def parse(self, html):
 65         selector = etree.HTML(html)
 66 
 67         # 返回所有段子的节点位置,contant()模糊查询方法,第一个参数是要匹配的标签,第二个参数是这个标签的部分内容
 68         # 每个节点包括一条完整的段子(用户名,段子内容,点赞,评论等)
 69         node_list = selector.xpath(‘//div[contains(@id,"qiushi_tag_")]‘)
 70 
 71         for node in node_list:
 72             # 爬取所有用户名信息
 73             # 取出标签里的内容,使用.text方法
 74             user_name = node.xpath(‘./div[@class="author clearfix"]//h2‘)[0].text
 75 
 76             # 爬取段子内容,匹配规则必须加点  不然还是会从整个页面开始匹配
 77             # 注意:如果span标签中有br 在插件中没问题,在代码中会把br也弄进来
 78             duanzi_info = node.xpath(‘.//div[@class="content"]/span‘)[0].text.strip()
 79 
 80             # 爬取段子的点赞数
 81             vote_num = node.xpath(‘.//span[@class="stats-vote"]/i‘)[0].text
 82 
 83             # 爬取评论数
 84             comment_num = node.xpath(‘.//span[@class="stats-comments"]//i‘)[0].text
 85 
 86             # 爬取图片链接
 87             # 属性src的值,所以不需要.text
 88             img_url = node.xpath(‘.//div[@class="thumb"]//@src‘)
 89             if len(img_url) > 0:
 90                 img_url = img_url[0]
 91             else:
 92                 img_url = "无图片"
 93 
 94             self.save_info(user_name, duanzi_info, vote_num, comment_num, img_url)
 95 
 96     def save_info(self, user_name, duanzi_info, vote_num, comment_num, img_url):
 97         """把每条段子的相关信息写进字典"""
 98         item = {
 99             "username": user_name,
100             "content": duanzi_info,
101             "zan": vote_num,
102             "comment": comment_num,
103             "image_url": img_url
104         }
105 
106         print(item)
107 
108 
109 
110 CRAWL_EXIT = False
111 PARSE_EXIT = False
112 
113 
114 def main():
115     # 页码的队列，表示20个页面
116     pageQueue = Queue(20)
117     # 放入1~10的数字，先进先出
118     for i in range(1, 21):
119         pageQueue.put(i)
120 
121     # 采集结果(每页的HTML源码)的数据队列，参数为空表示不限制
122     dataQueue = Queue()
123 
124     filename = open("duanzi.json", "a")
125     # 创建锁
126     lock = threading.Lock()
127 
128     # 三个采集线程的名字
129     crawlList = ["采集线程1号", "采集线程2号", "采集线程3号"]
130     # 存储三个采集线程的列表集合
131     thread_crawl = []
132     for threadName in crawlList:
133         thread = ThreadCrawl(threadName, pageQueue, dataQueue)
134         thread.start()
135         thread_crawl.append(thread)
136 
137 
138     # 三个解析线程的名字
139     parseList = ["解析线程1号","解析线程2号","解析线程3号"]
140     # 存储三个解析线程
141     thread_parse = []
142     for threadName in parseList:
143         thread = ThreadParse(threadName, dataQueue)
144         thread.start()
145         thread_parse.append(thread)
146 
147     # 等待pageQueue队列为空，也就是等待之前的操作执行完毕
148     while not pageQueue.empty():
149         pass
150 
151     # 如果pageQueue为空，采集线程退出循环
152     global CRAWL_EXIT
153     CRAWL_EXIT = True
154 
155     print("pageQueue为空")
156 
157     for thread in thread_crawl:
158         thread.join()
159 
160     while not dataQueue.empty():
161         pass
162 
163     global PARSE_EXIT
164     PARSE_EXIT = True
165 
166     for thread in thread_parse:
167         thread.join()
168 
169 
170 
171 if __name__ == "__main__":
172     main()