python设计模式第十九天【职责链模式】

1.应用场景

（1）将一个任务拆分为具有顺序的多个部分，每个类完成相应的部分，并且顺序执行

（2）软件窗口的消息传播

（3）SERVLET容积的过滤器Filter的实现

2.代码实现

#!/usr/bin/env python
#! _*_ coding:UTF-8 _*_

from abc import ABCMeta, abstractmethod

class Handler(object):

    @abstractmethod
    def handle(self):
        '''具体处理方法在子类中实现'''
        pass

    def handleNext(self):
        '''处理下一个'''
        if hasattr(self, "next_handler") and self.next_handler is not None:
            self.next_handler.handle()

    def setNextHanndler(self, next_handler):
        '''设置下一个处理器'''
        self.next_handler = next_handler

class OneHandler(Handler):

    def handle(self):
        print "one handle"
        self.handleNext()

class TwoHandler(Handler):

    def handle(self):
        print "two handle"
        self.handleNext()

class ThreeHandler(Handler):

    def handle(self):
        print "three handle"
        self.handleNext()

if __name__ == "__main__":
    oneHandler = OneHandler()

    twoHandler = TwoHandler()
    threeHandler = ThreeHandler()

    oneHandler.setNextHanndler(twoHandler)
    twoHandler.setNextHanndler(threeHandler)

    oneHandler.handle()

结果：

/Users/liudaoqiang/PycharmProjects/numpy/venv/bin/python /Users/liudaoqiang/Project/python_project/day19_cor/cor_test.py
one handle
two handle
three handle

Process finished with exit code 0

例如：库存报损报溢作废功能需要检测报损报溢是否已经生成了单据，如果生成了单据则提示先作废相关的单据，否则直接作废报损报溢

<?php
namespace core\models;

use \core\models\WmsProfitloss;

class WmsProfitlossDeleterContext{

    private $__profitlossModel;
    private $__firstHandler;

    public function __construct($profitlossModel)
    {
        $this->__profitlossModel = $profitlossModel;
    }

    public function getProfitlossModel(){
        return $this->__profitlossModel;
    }

    public function setFirstHandler(MyHandler $firstHandler){
        $this->__firstHandler = $firstHandler;
    }

    public function getFirstHandler(){
        return $this->__firstHandler;
    }

    public function request(){
        $checkGenSheetHandler = new CheckGenSheetHandler($this->getProfitlossModel());
        $deleteHandler = new DeleteHandler($this->getProfitlossModel());
        $checkGenSheetHandler->setNextHandler($deleteHandler);
        return $this->getFirstHandler()->handle();
    }
}

abstract class MyHandler{

    private $nextHandler;

    protected $__profitlossModel;

    public function __construct(WmsProfitloss $profitlossModel)
    {
        $this->__profitlossModel = $profitlossModel;
    }

    public abstract function handle();

    public function handleNext(){
        if (isset($this->nextHandler) && !empty($this->nextHandler)){
            return $this->nextHandler->handle();
        }
    }

    public function setNextHandler(MyHandler $nextHandler){
        $this->nextHandler = $nextHandler;
    }
}

class CheckGenSheetHandler extends MyHandler{

    public function handle(){
        $notDelSheetNumberList = $this->__profitlossModel->getGeneratedNotDelSheetNumberList();
        if (!empty($notDelSheetNumberList)){
            $notDelSheetNumberStr = implode(',', $notDelSheetNumberList);
            return ['status'=>true, 'errcode'=>'', 'errmsg'=>'请先作废单据'. $notDelSheetNumberStr];
        }
        return $this->handleNext();
    }
}

class DeleteHandler extends MyHandler{
    public function handle(){
        $handleResult = $this->__profitlossModel->delete();
        if ($handleResult){
            $this->handleNext();
        }
        if ($handleResult){
            return ['status'=>true, 'errcode'=>'', 'errmsg'=>'作废'.$this->__profitlossModel->wms_profitloss_code.'成功'];
        }else{
            return ['status'=>false, 'errcode'=>'', 'errmsg'=>'作废'.$this->__profitlossModel->wms_profitloss_code.'失败'];
        }
    }
}