将分隔字符串从infile写入输出文件

Question

目的是搜索infile（html）并重现可以传递给wget的outfile中任何图像的URL。这将是我用Python编写的第一个有用的东西，它似乎在Fedora上运行良好。我找不到任何特别的地方。有没有人有改善这方面的建议？

import fileinput 
import re 
#replace 'output.txt' with the name of your outfile 
file = open('output.txt', 'w') 

#prefix and postfix are how we discriminate your substring from the infile's line 
prefix = '<img src=' 
postfix = '.jpg' 

#read through the infile line-by-line 
for line in fileinput.input(): 
    if re.search(prefix, line): 
     #from if above, if you find the prefix, assign the integer to first_index 
     first_index = line.index(prefix) 
      if re.search(postfix, line): 
       #same as comment above, but for postfix 
       second_index = line.index(postfix) 
       #write your string plus an newline to the outfile 
       file.write(line[first_index+prefix.__len__():second_index+postfix.__len__()]+'\n') 

Answer 1

我在过去做过这样的事情，它工作得很好......我相信它会比试图用正则表达式解析更准确。

from HTMLParser import HTMLParser 


class ImageFinder(HTMLParser): 
    def __init__(self): 
     HTMLParser.__init__(self) 
     self.file = open('output.txt', 'w') 
    def handle_starttag(self, tag, attrs): 
     if tag == "img": 
      url = [u[1] for u in attrs if u[0] == "src"][0] 
      self.file.write(url+"\n") 
    def __exit__(self): 
     self.file.close() 

inputdata = open("myfile.txt").read() 
parser = ImageFinder() 
parser.feed(inputdata)