python---基于memcache的自定义session类

import config
import hashlib
import time
import memcache
import json

conn = memcache.Client(["127.0.0.1:8081"],debug=True)

class BaseSession:
    @classmethod
    def get_session_handler(cls,handler):
        if config.SESSION_TYPE == "Memery":
            obj = MemerySession(handler)
        elif config.SESSION_TYPE == "Mamcache":
            obj = MemcacheSession(handler)
        elif config.SESSION_TYPE == "Redis":
            obj = RedisSession(handler)
        return obj

class MemcacheSession:
    session_id = "py_session"

    def __init__(self,handler):
        self.handler = handler
        #从客户端获取随机字符串
        client_random_str = self.handler.get_cookie(MemcacheSession.session_id)
        #如果获取到了字符串
        if client_random_str and conn.get(client_random_str):
            self.random_str = client_random_str
        else:
            self.random_str = self.__genarate_random_str()
            conn.set(self.random_str,json.dumps({}),config.SESSION_EXPIRE)
        conn.set(self.random_str,conn.get(self.random_str),config.SESSION_EXPIRE)
        expires_time = time.time() + config.SESSION_EXPIRE
        handler.set_cookie(MemerySession.prex_str, self.random_str, expires=expires_time)

    def __setitem__(self, key, value):
        ret = conn.get(self.random_str)
        ret_dict = json.loads(ret)
        ret_dict[key]=value
        conn.set(self.random_str, json.dumps(ret_dict), config.SESSION_EXPIRE)

    def __getitem__(self, item):
        ret = conn.get(self.random_str)
        ret_dict = json.loads(ret)
        return ret_dict.get(item,None)

    def __delitem__(self, key):
        ret = conn.get(self.random_str)
        ret_dict = json.loads(ret)
        del ret_dict[key]
        conn.set(self.random_str, json.dumps(ret_dict), config.SESSION_EXPIRE)

    def __genarate_random_str(self):
        obj = hashlib.md5()
        obj.update(bytes(str(time.time()),encoding="utf8"))
        random_str=obj.hexdigest()
        return random_str