import urllib.request
import lxml.etree as etree
import datetime
def get_date_close_price(stocknum,date_string,date_format='%Y/%m/%d'):
    #ex:'2330','2015/8/24','%Y/%m/%d'
    #dateobj.strftime('%#m')可以 08 => 8 in windows
    #dateobj.strftime('%-m')可以 08 => 8 in linux?
    dateobj = datetime.datetime.strptime(date_string,date_format)
    #print(dateobj)
    stocknum = str(stocknum)
    try:
        data = urllib.request.urlopen('http://www.cnyes.com/twstock/ps_historyprice/'+str(stocknum)+'.htm').read().decode('utf-8',errors='ignores')
    except Exception as e:
        #return e.args
        return 'null'
    page = etree.HTML(data)
    #print(page)
    #print(dateobj.strftime('%Y/%m/%d'))
    try:
        return page.xpath('//tr/td[contains(text(),"'+ dateobj.strftime('%Y/%m/%d') +'")]/following-sibling::*')[3].text
    except Exception as e:
        #return e.args
        return 'null'
    #datetime.datetime.strptime('2015/8/24','%Y/%m/%d')
get_date_close_price('2330','2015/09/17')
#data = urllib.request.urlopen('http://www.cnyes.com/twstock/ps_historyprice/1101.htm').read().decode('utf-8',errors='ignores')
#page = etree.HTML(data)