利用python进行多线程爬虫

import threading
import time
import requests
import json
from queue import Queue
from lxml import etree


class CrawlThread(threading.Thread):
    ‘‘‘doc string for crawl thread‘‘‘

    def __init__(self, name, page_queue, data_queue):
        super(CrawlThread, self).__init__()
        self.name = name
        self.page_queue = page_queue
        self.data_queue = data_queue
        self.url = ‘http://www.ifanjian.net/latest-{}‘
        self.headers = {
            "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36",
        }

    def run(self):
        print(‘%s ------- 线程启动‘ % self.name)
        while True:
            # 判断采集线程何时结束
            if self.page_queue.empty():
                break
            # 从队列中取出页面
            page = self.page_queue.get()
            print("===采集===开始第%s页数据" % page)
            # 拼接url，发送请求
            url = self.url.format(page)
            time.sleep(1)
            r = requests.get(url, headers=self.headers)
            # 将响应内容存放到data_queue
            self.data_queue.put({
                "index": str(page),
                "text": r.text
            })
            print("===采集===结束第%s页数据" % page)

        print(‘%s ------- 线程结束‘ % self.name)


class ParserThread(threading.Thread):
    ‘‘‘doc string for parse thread‘‘‘

    def __init__(self, name, data_queue, fp, lock):
        super(ParserThread, self).__init__()
        self.name = name
        self.data_queue = data_queue
        self.fp = fp
        self.lock = lock

    def run(self):
        print(‘%s ------- 线程启动‘ % self.name)
        while True:
            try:
                # 从data_queue中取出数据
                data = self.data_queue.get(True, 10)
                print("===解析===开始第%s页数据" % data["index"])
                # 解析内容
                self.parse_content(data[‘text‘])
                print("===解析===开始第%s页数据" % data["index"])
            except Exception:
                break

        print(‘%s ------- 线程结束‘ % self.name)

    # 解析内容
    def parse_content(self, data):
        tree = etree.HTML(data)
        # 先找出所有的li，然后再从li中找到所有的标题和图片
        li_list = tree.xpath("//ul[@class=‘cont-list‘]/li")
        items = []
        for li in li_list:
            # 获取标题
            title = li.xpath(".//h2[@class=‘cont-list-title‘]/a/text()")[0]
            # 获取图片
            img_url = li.xpath(
                ".//div[contains(@class,‘cont-list-main‘)]//img/@data-src")
            item = {
                ‘标题‘: title,
                ‘图片链接‘: img_url
            }
            items.append(item)

        # 写到文件中
        self.lock.acquire()
        self.fp.write(json.dumps(items, ensure_ascii=False) + ‘\n‘)
        self.lock.release()


# 用来存放采集线程
g_crawl_list = []
# 用来存放解析线程
g_parser_list = []


def create_crawl_thread(page_queue, data_queue):
    crawl_names = [‘采集线程1‘, ‘采集线程2‘, ‘采集线程3‘]
    for name in crawl_names:
        tcrawl = CrawlThread(name, page_queue, data_queue)
        g_crawl_list.append(tcrawl)


def create_parser_thread(data_queue, fp, lock):
    parse_names = [‘解析线程1‘, ‘解析线程2‘, ‘解析线程3‘]
    for name in parse_names:
        tparse = ParserThread(name, data_queue, fp, lock)
        g_parser_list.append(tparse)


def create_queue():
    page_queue = Queue()
    for page in range(1, 10):
        page_queue.put(page)

    data_queue = Queue()

    return page_queue, data_queue


def main():
    # 创建队列
    page_queue, data_queue = create_queue()
    # 打开文件
    fp = open(‘jian.json‘, ‘a‘, encoding=‘utf-8‘)
    # 创建锁
    lock = threading.Lock()
    # 创建采集线程
    create_crawl_thread(page_queue, data_queue)
    # 创建解析线程
    create_parser_thread(data_queue, fp, lock)

    # 启动所有采集线程
    for tcrawl in g_crawl_list:
        tcrawl.start()
    # 启动所有解析线程
    for tparser in g_parser_list:
        tparser.start()

    # 主线程等待子线程结束
    for tcrawl in g_crawl_list:
        tcrawl.join()
    for tparser in g_parser_list:
        tparser.join()
    # 关闭文件
    fp.close()
    print("主线程和子线程全部结束.....")


if __name__ == "__main__":
    main()