责任链模式

责任链模式 当你想要让一个以上的对象有机会能够处理某个请求的时候，就使用责任链模式。

#include <iostream>

using namespace std;

class Handler {
public:
    Handler(Handler *successor=NULL) {this->successor = successor;}
    virtual ~Handler() {};
    virtual void handleRequest() = 0;
protected:
    Handler *successor;
};

class SpamHandler : public Handler {
public:
    SpamHandler(Handler *successor=NULL) : Handler(successor) {}
    ~SpamHandler() {}
    void handleRequest() {
        cout << "SpamHandler: handleRequest" << endl;
        if (NULL != successor) {
            successor->handleRequest();
        } else {
            cout << "end" <<endl;
        }
    }
};

class FanHandler : public Handler {
public:
    FanHandler(Handler *successor=NULL) : Handler(successor) {}
    ~FanHandler() {}
    void handleRequest() {
        cout << "FanHandler: handleRequest" << endl;
        if (NULL != successor) {
            successor->handleRequest();
        } else {
            cout << "end" <<endl;
        }
    }
};

class ComplaintHandler : public Handler {
public:
    ComplaintHandler(Handler *successor=NULL) : Handler(successor) {}
    ~ComplaintHandler() {}
    void handleRequest() {
        cout << "ComplaintHandler: handleRequest" << endl;
        if (NULL != successor) {
            successor->handleRequest();
        } else {
            cout << "end" <<endl;
        }
    }
};

class NewLocHandler : public Handler {
public:
    NewLocHandler(Handler *successor=NULL) : Handler(successor) {}
    ~NewLocHandler() {}
    void handleRequest() {
        cout << "NewLocHandler: handleRequest" << endl;
        if (NULL != successor) {
            successor->handleRequest();
        } else {
            cout << "end" <<endl;
        }
    }
};


int main(int argc, char **argv) {
    Handler *newLocHandler = new NewLocHandler();
    Handler *complaintHandler = new ComplaintHandler(newLocHandler);
    Handler *fanHandler = new FanHandler(complaintHandler);
    Handler *spamHandler = new SpamHandler(fanHandler);
    Handler *handler = spamHandler;

    handler->handleRequest();
}