chain_of_responsibility

责任链模式（Chain of Responsibility Pattern）是一种行为型设计模式，它允许多个对象按照顺序处理请求，直到其中一个对象能够处理为止。每个对象都可以决定是否处理请求，以及将请求传递给下一个对象。这种模式可以避免请求的发送者和接收者之间的耦合关系。

#include <iostream>

using namespace std;

class Handler {
public:
    virtual void setNext(Handler* handler) = 0;
    virtual void handleRequest(int request) = 0;
};

class HandlerA :public Handler {
private:
    Handler* nextHandler;
public:
    void setNext(Handler* handler) {
        nextHandler = handler;
    }
    void handleRequest(int request) {
        if (request >= 0 && request < 10) {
            cout << "HandlerA handleRequest" << endl;
        }
        else if (nextHandler != nullptr) {
            nextHandler->handleRequest(request);
        }
    }
};

class HandlerB :public Handler {
private:
    Handler* nextHandler;
public:
    void setNext(Handler* handler) {
        nextHandler = handler;
    }
    void handleRequest(int request) {
        if (request >= 10 && request < 20) {
            cout << "HandlerB handleRequest" << endl;
        }
        else if (nextHandler != nullptr) {
            nextHandler->handleRequest(request);
        }
    }
};

class HandlerC :public Handler {
private:
    Handler* nextHandler;
public:
    void setNext(Handler* handler) {
        nextHandler = handler;
    }
    void handleRequest(int request) {
        if (request >= 20 && request < 30) {
            cout << "HandlerC handleRequest" << endl;
        }
        else if (nextHandler != nullptr) {
            nextHandler->handleRequest(request);
        }
    }
};

int main() {
    Handler* handlerA = new HandlerA();
    Handler* handlerB = new HandlerB();
    Handler* handlerC = new HandlerC();
    handlerA->setNext(handlerB);
    handlerB->setNext(handlerC);
    handlerA->handleRequest(5);
    handlerA->handleRequest(15);
    handlerA->handleRequest(25);
    delete handlerA;
    delete handlerB;
    delete handlerC;
    return 0;
}

//HandlerA handleRequest
//HandlerB handleRequest
//HandlerC handleRequest

🐨 责任链模式(Chain of Responsibility 模式)