php程序员学习python3学习第十九天

1，单例模式

# -*- coding: utf-8 -*-
#单例模式  简单原理实现
class ConnectionPool:
    __instance = None #静态字段，存储首次实例后的对象
    def __init__(self):
        pass
    @staticmethod
    def getinstance():
        if ConnectionPool.__instance:
            return ConnectionPool.__instance
        else:
            ConnectionPool.__instance = ConnectionPool()
            return  ConnectionPool.__instance
    def get_connection(self):
        import random
        r = random.randrange(1,11)
        return r
for i in range(10):
    pool = ConnectionPool.getinstance()
    print('去连接池',pool)
    conn = pool.get_connection()
    print('获取到的连接是:',conn)