python版本的责任链模式

# -*- coding:UTF-8 -*-
import abc


class Handler(metaclass=abc.ABCMeta):
    def __init__(self):
        self._successor = None

    def set_successor(self, successor):
        self._successor = successor

    @abc.abstractmethod
    def handle_request(self, request):
        pass


class ConcreteHandler1(Handler):
    def handle_request(self, request):
        if request >= 0 and request < 10:
            print("{}处理请求{}".format(self.__class__.__name__, request))
        elif self._successor != None:
            self._successor.handle_request(request)


class ConcreteHandler2(Handler):
    def handle_request(self, request):
        if request >= 10 and request < 20:
            print("{}处理请求{}".format(self.__class__.__name__, request))
        elif self._successor is not None:
            self._successor.handle_request(request)


class ConcreteHandler3(Handler):
    def handle_request(self, request):
        if request >= 20 and request < 30:
            print("{}处理请求{}".format(self.__class__.__name__, request))
        elif self._successor is not None:
            self._successor.handle_request(request)


if __name__ == "__main__":
    h1 = ConcreteHandler1()
    h2 = ConcreteHandler2()
    h3 = ConcreteHandler3()

    h1.set_successor(h2)
    h2.set_successor(h3)

    requests = [2, 5, 14, 22, 18, 3, 27, 20]
    for request in requests:
        h1.handle_request(request)