class ConnectionPool

     __instance=None

     def__init__(self):

         self.ip="1.1.1.1"

         self.port=3307

         self.pwd=""

         self.username="minmin"

         self.conn_list=[1,2,3,4,5,6,7,8,9,10]

     @staticmethond

     def get_instance():

         if ConnectionPool.__instance:

             return ConnectionPool.__instance

         else:

             #/创建一个对象，并将对象赋值给静态字段__instance

             ConnectionPool.__instance=ConnectionPool()

             return ConnectionPool.__instance

      def get_coonection(self):

         #获取连接

           import random

           r =  random.randrange(1,11)

               return r

 obj1=ConnectPool.get_instance()

 print(obj1)

 obj2=ConnectPool.get_instance()

 print(obj2)

 obj3=ConnectPool.get_instance()

 print(obj3)                                

 #!/usr/bin/env python

 # -*- coding: utf-8 -*-

 form wsgiref.simple_server import make_server

 import random

 class ConnectionPool:

     __instance = None

 def __init__(self):

     self.ip = "1.1.1.1"

     self.port=3307

     self.pwd=""

     self.username=""

     self.conn_list = [1, 2, 3, 4, 5, 6, 7, 8, 9,10]

 @staticmethod

 def  get_instance():

     if ConnectionPool.__instance:

         return ConnectionPool.__instance

     else:

          # 创建一个对象，并将对象赋值给静态字段__instance

         ConnectionPool.__instance = ConnectionPool()

         return ConnectionPool.__instance

 def get_connection(self):

             #获取连接

     r =  random.randrange(1,11)

     return r

 def index():

     p = ConnectionPool.get_instance()

     print(p)

     conn = ConnectionPool.get_connection()

     return ""+str(conn)

 def news():

     return ""

 def RunServer(environ,start_response):

     start_response(status='200 OK',headers=[('Content-Type','text/html')])

     url=environ['PATH_INFO']

     if url.endswith('index'):

         ret = index()

         return ret

     elif url.endswith('news'):

         ret = news()

         return ret

     else:

         return ''

 if __name__=='__main__':

     httpd=make_server('', 8000, RunServer)

     print("Serving HTTP on port 8000.....")

     httpd.serve_forever()单例单例