python处理抓取中文编码和判断编码

#coding:utf-8
import chardet
#抓取网页html
line = "http://www.pythontab.com"
html_1 = urllib2.urlopen(line,timeout=120).read()
encoding_dict = chardet.detect(html_1)
print encoding
web_encoding = encoding_dict['encoding']
#处理，整个html就不会是乱码。
if web_encoding == 'utf-8' or web_encoding == 'UTF-8':
html = html_1
else :
html = html_1.decode('gbk','ignore').encode('utf-8')