命令模式

1、概念 ：

将一个请求封装成一个对象，从而让你使用不同的请求把客户端参数化，对请求队列或者记录请求日志，可以提供命令的撤销和恢复功能。

2、角色描述：

  

                      Receiver接受者角色，就是干活的码农，命令传递打这里就应该被执行。

                     Command命令角色，对命令额封装，所有命令声明在此

                     Invoker调用者角色，接受到命令并且执行命令。

3、适用范围：

将一个请求封装成一个对象，从而使你可用不同的请求对客户端进行参数化；对请求排队或记录请求日志，以及支持可撤销的操作。

4、示例代码：

//  命令模式 上#include<iostream>using namespace std;class Doctor{public:void  treat_eye(){cout << "医生治疗 眼科病" << endl;}void treat_nose(){cout << "医生治疗 鼻科病" << endl;}};// 这种方法医生和病人 的耦合度太高；假如医生生病了，那病人就没有人给看病。// 通过一个命令，通过命令执行来看病class CommandTreatEye{public:CommandTreatEye(Doctor *doctor){m_doctor = doctor;}void treat(){m_doctor->treat_eye();}private:Doctor *m_doctor;};class CommandTreatNose{public:CommandTreatNose(Doctor *doctor){m_doctor = doctor;}void treat(){m_doctor->treat_nose();}private:Doctor *m_doctor;};void test(){// 1、 医生直接看病// 这种方法医生和病人 的耦合度太高；假如医生生病了，那病人就没有人给看病。Doctor *doctor = new Doctor;doctor->treat_eye();delete doctor;doctor = NULL;// 2、通过命令来让 医生看病Doctor *doctor = new Doctor;CommandTreatEye *commandtreateye = new CommandTreatEye(doctor);   //ctrl+u 把所选中的的代码转换成小写；ctrl+Shift+u  把所选中的代码转换成大写commandtreateye->treat();delete doctor;delete commandtreateye;}int main(void){test();return 0;}// 命令模式下// 上面的两种方法，一种是医生直接看病 ，一种是医生可以通过命令来看病//  当医生越来越厉害，看病的人越来越多时。这时候就需要病号，通过排队来看病。//  这个时候就要来引入一个发起者，再添加一个护士类，护士可以把来看病的人的兵力 收集起来 给医生，医生 一个一个给看病#include<iostream>#include<list>using namespace std;class Doctor{public:void  treat_eye(){cout << "医生治疗 眼科病" << endl;}void treat_nose(){cout << "医生治疗 鼻科病" << endl;}};// 对命令进行一个抽象 ，面对抽象类编程class Command{public:virtual void treat() = 0;};// 这种方法医生和病人 的耦合度太高；假如医生生病了，那病人就没有人给看病。// 通过一个命令，通过命令执行来看病class CommandTreatEye:public Command{public:CommandTreatEye(Doctor *doctor){m_doctor = doctor;}void treat(){m_doctor->treat_eye();}private:Doctor *m_doctor;};class CommandTreatNose:public Command{public:CommandTreatNose(Doctor *doctor){m_doctor = doctor;}void treat(){m_doctor->treat_nose();}private:Doctor *m_doctor;};// 护士类来收集命令class BeautifulNurse{public:BeautifulNurse(Command *command){m_command = command;}// 提交病例，下达命令void SubmitteCase(){m_command->treat();}private:Command*   m_command;};void test(){// 1、 医生直接看病// 这种方法医生和病人 的耦合度太高；假如医生生病了，那病人就没有人给看病。Doctor *doctor = new Doctor;doctor->treat_eye();delete doctor;doctor = NULL;// 2、通过命令来让 医生看病doctor = new Doctor;Command *command = new CommandTreatEye(doctor);//ctrl+u 把所选中的的代码转换成小写；ctrl+Shift+u  把所选中的代码转换成大写command->treat();delete doctor;delete command;}// 添加护士长，负责收集10个命令// 护士长类class AdvHeadNurse{public:AdvHeadNurse(){m_list.clear();   // 清空链表}void setCommand(Command *command){m_list.push_back(command);}void SubmittedCase()    // 提交病例，下单 命令{for (list<Command*>::iterator it=m_list.begin();it!=m_list.end();++it){(*it)->treat();}}private:list<Command*>m_list;};void test2(){// 护士提交简历，给以上看病BeautifulNurse * beautiful = NULL;Doctor *doctor = NULL;Command *command = NULL;doctor = new Doctor;command = new CommandTreatNose(doctor);beautiful = new BeautifulNurse(command);beautiful->SubmitteCase();//ctrl+u 把所选中的的代码转换成小写；ctrl+Shift+u  把所选中的代码转换成大写command->treat();delete doctor;delete command;}// 通过护士长批量的下达命令void test3(){// 护士提交简历，给以上看病AdvHeadNurse * advHeadNurse = NULL;Doctor *doctor = NULL;Command *command1 = NULL;Command *command2 = NULL;doctor = new Doctor;command1 = new CommandTreatNose(doctor);command2 = new CommandTreatEye(doctor);advHeadNurse = new AdvHeadNurse();   // new一个护士长,可以提交好多病例advHeadNurse->setCommand(command1);advHeadNurse->setCommand(command2);advHeadNurse->SubmittedCase();;delete doctor;delete command1;delete command2;delete advHeadNurse;}int main(void){test3();return 0;}