020 --- 第24章 职责链模式

简述：

　　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它为止。

　　职责链模式包括：处理请示接口类、具体处理者类。

　　　　处理请示接口类：定义处理请求的接口。

　　　　具体处理者类：继承自处理请示接口类，处理它所负责的请求，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。

职责链模式：

#include <iostream>
using namespace std;

// 处理请示接口类
class CHandler
{
protected:
    CHandler* m_pSuccessor;

public:
    void SetSuccessor(CHandler* pSuccessor)
    {
        m_pSuccessor = pSuccessor;
    }

    virtual void HandlerRequest(int nRquest) = 0;
};

// 具体处理者类
class CConcreteHandler1 : public CHandler
{
public:
    virtual void HandlerRequest(int nRquest)
    {
        if (nRquest >= 0 && nRquest < 10)
            cout << "Handler1 处理请求 " << nRquest << endl;
        else if (m_pSuccessor != NULL)
            m_pSuccessor->HandlerRequest(nRquest);
    }
};

// 具体处理者类
class CConcreteHandler2 : public CHandler
{
public:
    virtual void HandlerRequest(int nRquest)
    {
        if (nRquest >= 10 && nRquest < 20)
            cout << "Handler2 处理请求 " << nRquest << endl;
        else if (m_pSuccessor != NULL)
            m_pSuccessor->HandlerRequest(nRquest);
    }
};

// 具体处理者类
class CConcreteHandler3 : public CHandler
{
public:
    virtual void HandlerRequest(int nRquest)
    {
        if (nRquest >= 20 && nRquest < 30)
            cout << "Handler3 处理请求 " << nRquest << endl;
        else if (m_pSuccessor != NULL)
            m_pSuccessor->HandlerRequest(nRquest);
    }
};

int main()
{
    CConcreteHandler1 Handler1;
    CConcreteHandler2 Handler2;
    CConcreteHandler3 Handler3;
    Handler1.SetSuccessor(&Handler2);
    Handler2.SetSuccessor(&Handler3);

    int requests[] = {2, 5, 14, 22, 18, 3, 27, 20};

    for (auto request : requests)
        Handler1.HandlerRequest(request);

    system("pause");
    return 0;
}

输出结果：

例：员工请求加薪

代码如下：

#include <iostream>
using namespace std;

// 请求类
class CRequest
{
private:
    string m_szRequestType; // 申请类别
    string m_szRequestContent; // 申请内容
    int m_nNumber; // 数量

public:
    void SetRequestType(string szRequestType) { m_szRequestType = szRequestType; }

    string GetRequestType() { return m_szRequestType; }

    void SetRequestContent(string szRequestContent) { m_szRequestContent = szRequestContent; }

    string GetRequestContent() { return m_szRequestContent; }

    void SetNumber(int nNumber) { m_nNumber = nNumber; }

    int GetNumber() { return m_nNumber; }
};

// 管理者（处理请示接口类）
class CManager
{
protected:
    string m_szName;
    CManager* m_pSuperior; // 管理者上级

public:
    CManager(string szName) { m_szName = szName; }

    // 设置管理者上级
    void SetSuperior(CManager* pSuperior)     { m_pSuperior = pSuperior; }

    // 处理请求
    virtual void RequestApplications(CRequest* pRequest) = 0;
};

// 经理（具体处理类）
class CCommonManager : public CManager
{
public:
    CCommonManager(string name) : CManager(name) {}

    virtual void RequestApplications(CRequest* pRequest)
    {
        if (pRequest->GetRequestType() == "请假" && pRequest->GetNumber() <= 2)
            cout << m_szName << ":" << pRequest->GetRequestContent() << " 数量 " << pRequest->GetNumber() << " 被批准" << endl;
        else
        {
            if (m_pSuperior != NULL)
                m_pSuperior->RequestApplications(pRequest);
        }
    }
};

// 总监（具体处理类）
class CMajordomo: public CManager
{
public:
    CMajordomo(string name) : CManager(name) {}

    virtual void RequestApplications(CRequest* pRequest)
    {
        if (pRequest->GetRequestType() == "请假" && pRequest->GetNumber() <= 5)
            cout << m_szName << ":" << pRequest->GetRequestContent() << " 数量 " << pRequest->GetNumber() << " 被批准" << endl;
        else
        {
            if (m_pSuperior != NULL)
                m_pSuperior->RequestApplications(pRequest);
        }
    }
};

// 总经理（具体处理类）
class CGeneralManager : public CManager
{
public:
    CGeneralManager(string name) : CManager(name) {}

    virtual void RequestApplications(CRequest* pRequest)
    {
        if (pRequest->GetRequestType() == "请假")
            cout << m_szName << ":" << pRequest->GetRequestContent() << " 数量 " << pRequest->GetNumber() << " 被批准" << endl;
        else if (pRequest->GetRequestType() == "加薪" && pRequest->GetNumber() <= 500)
            cout << m_szName << ":" << pRequest->GetRequestContent() << " 数量 " << pRequest->GetNumber() << " 被批准" << endl;
        else if (pRequest->GetRequestType() == "加薪" && pRequest->GetNumber() > 500)
            cout << m_szName << ":" << pRequest->GetRequestContent() << " 数量 " << pRequest->GetNumber() << " 再说吧" << endl;
    }
};

int main()
{
    CCommonManager JinLi("金利");
    CMajordomo ZongJian("宗剑");
    CGeneralManager ZhongJingLi("钟精励");
    JinLi.SetSuperior(&ZongJian);
    ZongJian.SetSuperior(&ZhongJingLi);

    CRequest Request;
    Request.SetRequestType("请假");
    Request.SetRequestContent("GHL请假");
    Request.SetNumber(1);
    JinLi.RequestApplications(&Request);

    CRequest Request2;
    Request2.SetRequestType("请假");
    Request2.SetRequestContent("GHL请假");
    Request2.SetNumber(4);
    JinLi.RequestApplications(&Request2);

    CRequest Request3;
    Request3.SetRequestType("加薪");
    Request3.SetRequestContent("GHL请求加薪");
    Request3.SetNumber(500);
    JinLi.RequestApplications(&Request3);

    CRequest Request4;
    Request4.SetRequestType("加薪");
    Request4.SetRequestContent("GHL请求加薪");
    Request4.SetNumber(1000);
    JinLi.RequestApplications(&Request4);

    system("pause");
    return 0;
}

输出结果：