python 基础 9.2 设计模式之单例模式

设计模式

一、单例模式

单例，顾名思义单个实例。

#!/usr/bin/env python
# _*_ coding:utf-8 _*_
__author__ = 'liujianzuo'

class ConnectionPoll:
    __instance = None

    def __init__(self):
        self.ip = "1.1.1.1"
        self.port = 3306
        self.pwd = 123
        self.username = "root"

        self.conn_list = [1,2,3,4,5,6,7]

    @staticmethod
    def get_instance():
        if ConnectionPoll.__instance:
            return ConnectionPoll.__instance
        else:
            ConnectionPoll.__instance = ConnectionPoll()
            return ConnectionPoll.__instance

obj1 = ConnectionPoll.get_instance()
print(obj1)
obj2 = ConnectionPoll.get_instance()
print(obj2)
obj2= ConnectionPoll.get_instance()
print(obj2)