def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def _GetOutputStream(output_format, output_dir):
  assert output_format in _OUTPUT_FORMAT_CHOICES, 'Must specify a valid format.'
  assert output_format not in ('gtest', 'none'), (
      'Cannot set stream for \'gtest\' or \'none\' output formats.')

  if output_format == 'buildbot':
    return sys.stdout

  assert output_format in _OUTPUT_FILENAME_LOOKUP, (
      'No known filename for the \'%s\' output format' % output_format)
  output_file = os.path.join(output_dir, _OUTPUT_FILENAME_LOOKUP[output_format])
  open(output_file, 'a').close()  # Create file if it doesn't exist.
  return open(output_file, 'r+')