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 __getitem__(self, key):
        value = self._collection[key]
        if isinstance(key, slice):
            slice_repr = ":".join(str("" if i is None else i) for i in (key.start, key.stop, key.step))
            logger.debug("Get /%s[%s] config key", "/".join(self._path), slice_repr)
            return [self._to_python(item) for item in value]
        else:
            logger.debug("Get /%s[%s] config key", "/".join(self._path), key)
            return self._to_python(value)