Python使用正则表达式实现文本替换的方法

# encoding: UTF-8
import re
# 将正则表达式编译成Pattern对象
p = re.compile(r'(?P<folder>(\w+/)*)(?P<filename>\w+\.png)')
# 使用Pattern匹配文本，获得匹配结果，无法匹配时将返回None
#match = pattern.match('<key>xxx/duobaojiemian_L/yangpizi.png</key>')
the_str = """<key>XXXX/duobaojiemian2222_L/duobaojiemian_L/yangpizi.png</key>
 <key>yangpizi2.png</key>
 <key>yangpizi3.png</key> """
for m in p.finditer(the_str):
 # 使用Match获得分组信息
 print m.groupdict()
print '-------------------------------'
#f = lambda m: m.group().find('XXXX/') == -1 and 'XXXX/'+m.group() or m.group()
def f(m):
 s = m.group()
 return s.find('XXXX/') == -1 and 'XXXX/'+s or s
def f2(m2):
 d = m2.groupdict()
 return d['folder']+'the_'+d['filename']
print p.sub(f2, the_str)