python实现多线程爬虫

mkdir mutiThreadCrawier
cd  mutiThreadCrawier
mkdir content #存爬下来的页面
virtualenv env --python =python3.6 #创建虚拟环境
source env/bin/activate   #使虚拟环境生效

import time
import re
import threading
import urllib
import requests
from bs4 import BeautifulSoup

g_mutex = threading.Condition()  # 可以加锁/释放锁
print(g_mutex)
print(type(g_mutex))
g_urls = []  # 存放解析出来的url对应的网页源码
g_queue_urls = [] # 待爬取的url
g_exist_urls = []  # 已经爬过的url
g_failed_urls = [] # 失败的链接
g_total_count = 0  # 已经下载的页面的计数器

class CrawlerThread(threading.Thread):


    def __init__(self,url,filename,tid):
        threading.Thread.__init__(self)
        self.filename=filename
        self.url =url
        self.tid=tid
    def run(self):
        try:
            resp=urllib.request.urlopen(self.url)
            html=resp.read()
            with open('content/'+self.filename,'wb') as f:

                f.write(html)
        except Exception as e:
            g_exist_urls.append(self.url)
            g_failed_urls.append(self.url)
            print(f'页面{self.url}下载失败！')
        g_mutex.acquire()
        g_urls.append(html)
        g_exist_urls.append(self.url)
        g_mutex.release()

class Crawler:
    def __init__(self,name,domain,thread_number):
        self.name=name

        self.domain=domain
        self.thread_number=thread_number

        self.logfile=open('log.txt','w')
        self.thread_pool=[]
        self.url = 'http://'+domain

     def spider(self):# 内容会随着爬虫的进行而更新
        global g_queue_urls# 初始，队列中仅有一个url
        g_queue_urls.append(self.url)# 爬取的深度
        depth =0
        print(f'爬虫{self.name}开始启动........')
        while g_queue_urls:
            depth +=1
            print(f'当前爬取深度是{depth}')
            self.logfile.write(f'URL:{g_queue_urls[0]}')
            self.download_all() # 下载所有
            self.update_queque_url() # 更新 url队列
            self.logfile.write(f">>>Depth:{depth}")
            count = 0
            while count <len(g_queue_urls):
                self.logfile.write(f"累计爬取{g_total_count}条，爬取是第{g_queue_urls[count]}个")
                count+=1



    def download_all(self):
        global g_queue_urls
        global g_total_count
        i=0
        while i < len(g_queue_urls):
            j=0
            while j<self.thread_number and i+j <len(g_queue_urls):
                g_total_count +=1
                print(g_queue_urls[i+j])
                thread_result=self.download(g_queue_urls[i+j],f"{g_total_count}.html",j)
                if thread_result  is not None:
                      print(f'线程{i+j}启动')
                j +=1
            i=i+j
            for thread in self.thread_pool:
                thread.join(25)
        g_queue_urls=[]



    def download(self,url,filename,tid):
        print(url,filename,tid)
        creawler_thread= CrawlerThread(url,filename,tid)
        self.thread_pool.append(creawler_thread)
        creawler_thread.start()
    def update_queque_url(self):
        global g_queue_urls
        global g_exist_urls#已经爬过的url
        new_urls=[]#新发现的url
        for url_content in g_urls:
            new_urls +=self.get_Url(url_content)# 从页面中提取新url
        g_queue_urls=list(set(new_urls)  -set(g_exist_urls)) # 去除重复的和已经爬过的

    def get_Url(self,content):
    	'''
        从网页源代码中提取url
        '''
        links =[] # 保存提取到的href
        try:

            soup =BeautifulSoup(content)
            for link in soup.findAll('a'):
                if link is not None and link.get('href') is not None:
                    if self.domain in link['href']:
 			# 如果link是本网站的绝对地址
                        links.append(link)
                    elif  len(link['href']) >10 and  'http://' not in link['href']:
				 # 如果link是相对地址
                        links.append(self.url +link['href'])



        except Exception as e:
            print("fail to get url",e)
        return links

if __name__=="__main__":
    domain ="www.geyanw.com"
    thread_number=10
    name="geyan"
    crawler =Crawler(name,domain,thread_number)
    crawler.spider()