基python实现多线程网页爬虫

#!/usr/bin/env python#coding=utf-8import threadingimport urllibimport reimport timeg_mutex=threading.Condition()g_pages=[] #从中解析所有url链接g_queueURL=[] #等待爬取的url链接列表g_existURL=[] #已经爬取过的url链接列表g_failedURL=[] #下载失败的url链接列表g_totalcount=0 #下载过的页面数class Crawler:  def __init__(self,crawlername,url,threadnum):    self.crawlername=crawlername    self.url=url    self.threadnum=threadnum    self.threadpool=[]    self.logfile=file("log.txt",'w')  def craw(self):    global g_queueURL    g_queueURL.append(url)      depth=0    print self.crawlername+" 启动..."    while(len(g_queueURL)!=0):      depth+=1      print 'Searching depth ',depth,'.../n/n'      self.logfile.write("URL:"+g_queueURL[0]+"........")      self.downloadAll()      self.updateQueueURL()      content='/n>>>Depth '+str(depth)+':/n'      self.logfile.write(content)      i=0      while i<len(g_queueURL):        content=str(g_totalcount+i)+'->'+g_queueURL[i]+'/n'        self.logfile.write(content)        i+=1  def downloadAll(self):    global g_queueURL    global g_totalcount    i=0    while i<len(g_queueURL):      j=0      while j<self.threadnum and i+j < len(g_queueURL):        g_totalcount+=1        threadresult=self.download(g_queueURL[i+j],str(g_totalcount)+'.html',j)        if threadresult!=None:          print 'Thread started:',i+j,'--File number =',g_totalcount        j+=1      i+=j      for thread in self.threadpool:        thread.join(30)      threadpool=[]    g_queueURL=[]  def download(self,url,filename,tid):    crawthread=CrawlerThread(url,filename,tid)    self.threadpool.append(crawthread)    crawthread.start()  def updateQueueURL(self):    global g_queueURL    global g_existURL    newUrlList=[]    for content in g_pages:      newUrlList+=self.getUrl(content)    g_queueURL=list(set(newUrlList)-set(g_existURL))    def getUrl(self,content):    reg=r'"(http://.+?)"'    regob=re.compile(reg,re.DOTALL)    urllist=regob.findall(content)    return urllistclass CrawlerThread(threading.Thread):  def __init__(self,url,filename,tid):    threading.Thread.__init__(self)    self.url=url    self.filename=filename    self.tid=tid  def run(self):    global g_mutex    global g_failedURL    global g_queueURL    try:      page=urllib.urlopen(self.url)      html=page.read()      fout=file(self.filename,'w')      fout.write(html)      fout.close()    except Exception,e:      g_mutex.acquire()      g_existURL.append(self.url)      g_failedURL.append(self.url)      g_mutex.release()      print 'Failed downloading and saving',self.url      print e      return None    g_mutex.acquire()    g_pages.append(html)    g_existURL.append(self.url)    g_mutex.release()if __name__=="__main__":  url=raw_input("请输入url入口:/n")  threadnum=int(raw_input("设置线程数:"))  crawlername="小小爬虫"  crawler=Crawler(crawlername,url,threadnum)  crawler.craw()