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责任链模式和状态模式

news 2025/11/26 14:12:00

责任链模式和状态模式
共同点
核心逻辑, 都是在本类中, 包含另外一个能处理该逻辑的类, 如果本类无法处理, 就用另外一个类来处理
, 直至最终找到能够处理该逻辑的类,
不同点
有的说是责任链模式是客户端设置的下一级处理类, 状态模式是类中设置好的下个状态
其实根本逻辑都是差不多的, 只不过是下一级处理类的设置的阶段不通而已.

责任链模式

我们设置三个不同级别的身份
班长: 处理level <= 1的事务
教师: 处理level == 2的事务
校长: 处理所有级别的事务
然后在客户端( main方法里, 不是模式代码中 )分别设置他们的上一级处理人, 代码如下

class Processor
{
public:Processor* p;void set_superior(Processor* _p) { p = _p; }virtual void process(int level) = 0;
};class Monitor : public Processor
{
public:void process(int level) override{if (level <= 1)cout << "monitor can process this" << endl;elsep->process(level);}
};class Teacher : public Processor
{
public:void process(int level) override{if (level <= 2)cout << "teacher can process this" << endl;elsep->process(level);}
};class Headmaster : public Processor
{
public:void process(int level) override{cout << "Headmaster process this" << endl;}
};int main()
{Monitor* m = new Monitor();Teacher* t = new Teacher();Headmaster* h = new Headmaster();m->set_superior(t);t->set_superior(h);m->process(3);return 0;
}

执行结果
在这里插入图片描述

状态模式

状态模式的状态切换, 都是状态内部设置的, 客户端不用管
例如工作状态, 分为
早上: 10点前
中午: 13点前
下午: 18点前
晚上: 18点后
它们之间的状态切换会默认执行, 如下所示

class WorkState
{
public:virtual WorkState* work(int hour) = 0;
};class NightState : public WorkState
{
public:WorkState* work(int hour) override{if (hour < 19){cout << "time to dinner" << endl;}else{cout << "time to off work" << endl;}return this;}
};class AfternoonState : public WorkState
{
public:WorkState* work(int hour) override{if (hour < 18){cout << "afternoon time, good to work" << endl;return this;}else{WorkState* res = new NightState();res = res->work(hour);return res;}}
};class NoonState : public WorkState
{
public:WorkState* work(int hour) override{if (hour < 13){cout << "not time to noon sleep" << endl;return this;}else{WorkState* res = new AfternoonState();res = res->work(hour);return res;}}
};class ForenoonState : public WorkState
{
public:WorkState* work(int hour) override{if (hour < 10){cout << "not time to work" << endl;return this;}else if (hour < 12){cout << "forenoon time to work" << endl;return this;}else{WorkState* res = new NoonState();res = res->work(hour);return res;}}
};int main()
{WorkState* ws = new ForenoonState();ws = ws->work(7);ws = ws->work(11);ws = ws->work(12);ws = ws->work(15);ws = ws->work(19);return 0;
}