_compile(pattern, flags).findall(string) TypeError: cannot use a string pattern on a bytes-like

最近在自学python，做的一个图片爬虫，却出现一些错误，特此总结下来，为了别人遇到同样错误时可以快速解决同样的问题。

#coding=utf-8
import urllib
import urllib.request
import re

url = "http://tieba.baidu.com/p/2460150866"
page = urllib.request.urlopen(url)
html = page.read()
print(html)

#正则匹配
reg = r'src="(.+?\.jpg)" pic_ext'
imgre = re.compile(reg)
imglist = re.findall(imgre, html)
x = 0
print("start dowload pic")
for imgurl in imglist:
print(imgurl)
resp = urllib.request.urlopen(imgurl)
respHtml = resp.read()
picFile = open('%s.jpg' % x, "wb")
picFile.write(respHtml)
picFile.close()
x = x+1
print("done")

报错信息如下：



File “C:\Python35\lib\re.py”, line 213, in findall

return _compile(pattern, flags).findall(string)

TypeError: cannot use a string pattern on a bytes-like object

出错的主要原因是因为：

TypeError: can’t use a string pattern on a bytes-like object.

html用decode(‘utf-8’)进行解码，由bytes变成string。

py3的urlopen返回的不是string是bytes。

解决方法是：把’html’类型调整一下：html.decode(‘utf-8’)



正确代码如下：

#coding=utf-8
import urllib
#在python3.3里面，用urllib.request代替urllib2
import urllib.request
import re

url = "http://tieba.baidu.com/p/2460150866"
page = urllib.request.urlopen(url)
html = page.read()
print(html)    #python3中只能用print(html) python2中能写print html

#正则匹配
reg = r'src="(.+?\.jpg)" pic_ext'
imgre = re.compile(reg)
imglist = re.findall(imgre, html.decode('utf-8'))
x = 0
print("start dowload pic")
for imgurl in imglist:
print(imgurl)
resp = urllib.request.urlopen(imgurl)
respHtml = resp.read()
picFile = open('%s.jpg' % x, "wb")
picFile.write(respHtml)
picFile.close()
x = x+1
print("done")