def spider(beginurl,pages,downFolder):
priQueue = PriorityQueue()
downlist = PriorityQueue()
priQueue.push((1,beginurl))
i = 0
while not priQueue.empty() and i <pages:
k,url = priQueue.pop()
if downloadUrl(i+1,url,priQueue,downlist,downFolder,beginurl):
i+=1
print '\nDownload',i,'pages.'