本文实例讲述了python实现的用于搜索文件并进行内容替换的类。分享给大家供大家参考。具体实现方法如下：

#!/usr/bin/python -O
# coding: UTF-8
\"\"\"
-replace string in files (recursive)
-display the difference.
v0.2
 - search_string can be a re.compile() object -> use re.sub for replacing
v0.1
 - initial version
  Useable by a small \"client\" script, e.g.:
-------------------------------------------------------------------------------
#!/usr/bin/python -O
# coding: UTF-8
import sys, re
#sys.path.insert(0,\"/path/to/git/repro/\") # Please change path
from replace_in_files import SearchAndReplace
SearchAndReplace(
  search_path = \"/to/the/files/\",
  # e.g.: simple string replace:
  search_string = \'the old string\',
  replace_string = \'the new string\',
  # e.g.: Regular expression replacing (used re.sub)
  #search_string = re.compile(\'{% url (.*?) %}\'),
  #replace_string = \"{% url \'\\g<1>\' %}\",
  search_only = True, # Display only the difference
  #search_only = False, # write the new content
  file_filter=(\"*.py\",), # fnmatch-Filter
)
-------------------------------------------------------------------------------
:copyleft: 2009-2011 by Jens Diemer
\"\"\"
__author__ = \"Jens Diemer\"
__license__ = \"\"\"GNU General Public License v3 or above -
 http://www.opensource.org/licenses/gpl-license.php\"\"\"
__url__ = \"http://www.jensdiemer.de\"
__version__ = \"0.2\"
import os, re, time, fnmatch, difflib
# FIXME: see http://stackoverflow.com/questions/4730121/cant-get-an-objects-class-name-in-python
RE_TYPE = type(re.compile(\"\"))
class SearchAndReplace(object):
  def __init__(self, search_path, search_string, replace_string,
                    search_only=True, file_filter=(\"*.*\",)):
    self.search_path = search_path
    self.search_string = search_string
    self.replace_string = replace_string
    self.search_only = search_only
    self.file_filter = file_filter
    assert isinstance(self.file_filter, (list, tuple))
    # FIXME: see http://stackoverflow.com/questions/4730121/cant-get-an-objects-class-name-in-python
    self.is_re = isinstance(self.search_string, RE_TYPE)
    print \"Search \'%s\' in [%s]...\" % (
      self.search_string, self.search_path
    )
    print \"_\" * 80
    time_begin = time.time()
    file_count = self.walk()
    print \"_\" * 80
    print \"%s files searched in %0.2fsec.\" % (
      file_count, (time.time() - time_begin)
    )
  def walk(self):
    file_count = 0
    for root, dirlist, filelist in os.walk(self.search_path):
      if \".svn\" in root:
        continue
      for filename in filelist:
        for file_filter in self.file_filter:
          if fnmatch.fnmatch(filename, file_filter):
            self.search_file(os.path.join(root, filename))
            file_count += 1
    return file_count
  def search_file(self, filepath):
    f = file(filepath, \"r\")
    old_content = f.read()
    f.close()
    if self.is_re or self.search_string in old_content:
      new_content = self.replace_content(old_content, filepath)
      if self.is_re and new_content == old_content:
        return
      print filepath
      self.display_plaintext_diff(old_content, new_content)
  def replace_content(self, old_content, filepath):
    if self.is_re:
      new_content = self.search_string.sub(self.replace_string, old_content)
      if new_content == old_content:
        return old_content
    else:
      new_content = old_content.replace(
        self.search_string, self.replace_string
      )
    if self.search_only != False:
      return new_content
    print \"Write new content into %s...\" % filepath,
    try:
      f = file(filepath, \"w\")
      f.write(new_content)
      f.close()
    except IOError, msg:
      print \"Error:\", msg
    else:
      print \"OK\"
    print
    return new_content
  def display_plaintext_diff(self, content1, content2):
    \"\"\"
    Display a diff.
    \"\"\"
    content1 = content1.splitlines()
    content2 = content2.splitlines()
    diff = difflib.Differ().compare(content1, content2)
    def is_diff_line(line):
      for char in (\"-\", \"+\", \"?\"):
        if line.startswith(char):
          return True
      return False
    print \"line | text\\n-------------------------------------------\"
    old_line = \"\"
    in_block = False
    old_lineno = lineno = 0
    for line in diff:
      if line.startswith(\" \") or line.startswith(\"+\"):
        lineno += 1
      if old_lineno == lineno:
        display_line = \"%4s | %s\" % (\"\", line.rstrip())
      else:
        display_line = \"%4s | %s\" % (lineno, line.rstrip())
      if is_diff_line(line):
        if not in_block:
          print \"...\"
          # Display previous line
          print old_line
          in_block = True
        print display_line
      else:
        if in_block:
          # Display the next line aber a diff-block
          print display_line
        in_block = False
      old_line = display_line
      old_lineno = lineno
    print \"...\"
if __name__ == \"__main__\":
  SearchAndReplace(
    search_path=\".\",
    # e.g.: simple string replace:
    search_string=\'the old string\',
    replace_string=\'the new string\',
    # e.g.: Regular expression replacing (used re.sub)
    #search_string  = re.compile(\'{% url (.*?) %}\'),
    #replace_string = \"{% url \'\\g<1>\' %}\",
    search_only=True, # Display only the difference
#    search_only   = False, # write the new content
    file_filter=(\"*.py\",), # fnmatch-Filter
  )

希望本文所述对大家的Python程序设计有所帮助。