职责链模式

Posted 2022-03-29 manual-linux

一 概念

• 职责链模式，使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这个对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理他为止。

二 UML图

• Handler 定义一个处理请示的接口
• ConcreteHandler1, ConcreteHandler2 具体处理类，处理它负责的请求，可访问它的后继者，如果可处理该请求，就处理之，否则就将该请求转发给它的后继者。

三 职责链的好处

• 接收者和发送者都没有对方的明确信息，且链中的对象自己也并不知道链的结构。结果是职责链可以简化对象的相互连接，他们仅保持一个指向后继者的引用，而不需要保持它所有的候选接收者的引用。
• 可以随时地增加或修改处理一个请求的结构，增强了给对象指派职责的灵活性。
• 不过也应当小心，一个请求极有可能到了链的末端都得不到处理，或者因为没有正确配置而得不到处理。

四 C++代码实现

#include "pch.h"
#include <iostream>
#include <string>
using namespace std;

class Request

public:
    void SetRequestType(string type)
    
        this->m_requestType = type;
    
    string GetRequestType()
    
        return this->m_requestType;
    
    void SetRequestContent(string content)
    
        this->m_requestContent = content;
    
    string GetRequestContent()
    
        return this->m_requestContent;
    
    void SetRequestNumber(int number)
    
        this->m_number = number;
    
    int GetRequestNumber() const
    
        return this->m_number;
    
private:
    string m_requestType;  //申请类别
    string m_requestContent;  //申请内容
    int m_number; //申请的数量
;

class Manager

public:
    Manager(string name)
    
        this->m_name = name;
    
    //设置管理者的上级
    void SetSuperior(Manager* superior)
    
        this->m_superior = superior;
    
    //申请请求
    virtual void RequestApplications(Request* request) = 0;
protected:
    string m_name;
    Manager* m_superior;  //管理者的上级
;
//经理
class CommonManager : public Manager

public:
    CommonManager(string str)
        :Manager(str)
    

    
    void RequestApplications(Request* request) override
    
        //经理所能有的权限就是可准许下属两天内的假期
        if (request->GetRequestType() == "请假" && request->GetRequestNumber() <= 2)
        
            cout << this->m_name << ' ' << request->GetRequestContent() << " 数量" << request->GetRequestNumber() << " 被批准" << endl;
        
        else
        
            //其余的请求都需要转到上级
            if (this->m_superior != nullptr)
            
                this->m_superior->RequestApplications(request);
            
        
    
;

//总监
class Majordomo : public Manager

public:
    Majordomo(string str)
        :Manager(str)
    

    
    void RequestApplications(Request* request) override
    
        //经理所能有的权限就是可准许下属两天内的假期
        if (request->GetRequestType() == "请假" && request->GetRequestNumber() <= 5)
        
            cout << this->m_name << ' ' << request->GetRequestContent() << " 数量" << request->GetRequestNumber() << " 被批准" << endl;
        
        else
        
            //其余的请求都需要转到上级
            if (this->m_superior != nullptr)
            
                this->m_superior->RequestApplications(request);
            
        
    
;

//总经理的权限是全部都需要处理
class GeneralManager : public Manager

public:
    GeneralManager(string str)
        :Manager(str)
    

    
    void RequestApplications(Request* request) override
    
        //经理所能有的权限就是可准许下属两天内的假期
        if (request->GetRequestType() == "请假")
        
            cout << this->m_name << ' ' << request->GetRequestContent() << " 数量" << request->GetRequestNumber() << " 被批准" << endl;
        
        else if(request->GetRequestType() == "加薪" && request->GetRequestNumber() <= 500)
        
            cout << this->m_name << ' ' << request->GetRequestContent() << " 数量" << request->GetRequestNumber() << " 被批准" << endl;
        
        else if (request->GetRequestType() == "加薪" && request->GetRequestNumber() > 500)
        
            cout << this->m_name << ' ' << request->GetRequestContent() << " 数量" << request->GetRequestNumber() << " 再说吧" << endl;
        
    
;
int main()

    CommonManager* jinli = new CommonManager("经理");
    Majordomo* zongjian = new Majordomo("总监");
    GeneralManager* zongjingli = new GeneralManager("总经理");
    //设置上级，完全可以根据实际需要来更改设置
    jinli->SetSuperior(zongjian);
    zongjian->SetSuperior(zongjingli);

    //  
    Request* request = new Request();
    request->SetRequestType("请假");
    request->SetRequestContent("小菜请假");
    request->SetRequestNumber(1);
    jinli->RequestApplications(request);

    Request* request2 = new Request();
    request2->SetRequestType("请假");
    request2->SetRequestContent("小菜请假");
    request2->SetRequestNumber(4);
    jinli->RequestApplications(request2);

    Request* request3 = new Request();
    request3->SetRequestType("加薪");
    request3->SetRequestContent("小菜加薪");
    request3->SetRequestNumber(400);
    jinli->RequestApplications(request3);

    Request* request4 = new Request();
    request4->SetRequestType("加薪");
    request4->SetRequestContent("小菜加薪");
    request4->SetRequestNumber(1000);
    jinli->RequestApplications(request4);

    return 0;