设计模式之「观察者」模式

/* common.h */
#ifndef __COMMON_H__
#define __COMMON_H__
enum INFO_TYPE{
 NONE,
 RESOURCE,
 HELP
};
#endif
/* AllyCenter.h */
#ifndef __ALLYCENTER_H__
#define __ALLYCENTER_H__
#include "common.h"
#include <vector>
// 前向声明
class Observer;
class Player;
// 抽象目标：联盟中心
class AllyCenter
{
public:
 AllyCenter();
 // 声明通知方法
 virtual void notify(INFO_TYPE infoType, std::string name) = 0;
 // 加入玩家
 void join(Observer* player);
 // 踢出玩家
 void remove(Observer* player);
protected:
 // 玩家列表
 std::vector<Observer*>playerList;
};
// 具体目标
class AllyCenterController :public AllyCenter
{
public:
 AllyCenterController();
 // 实现通知方法
 void notify(INFO_TYPE infoType, std::string name);
};
#endif
/* Observer.h */
#ifndef __OBSERVER_H__
#define __OBSERVER_H__
#include <iostream>
using namespace std;
#include "common.h"
#include "AllyCenter.h"
// 抽象观察者 Observer
class Observer
{
public:
 Observer(){}
 // 声明抽象方法
 virtual void call(INFO_TYPE infoType, AllyCenter* ac) = 0;
 string getName(){
  return name;
 }
 void setName(string iName){
  this->name = iName;
 }
private:
 string name;
};
// 具体观察者 
class Player :public Observer
{
public:
 Player(){
  setName("none");
 }
 Player(string iName){
  setName(iName);
 }
 // call()具体实现
 void call(INFO_TYPE infoType, AllyCenter* ac){
  switch (infoType){
  case RESOURCE:
   printf("%s: 发现物资，快来~\n", getName().c_str());
   break;
  case HELP:
   printf("%s: 救救我~\n", getName().c_str());
   break;
  default:
   printf("Everything is ok!\n");
  }
  ac->notify(infoType, getName());
 }
 // 救助队友方法help()
 void help(){
  printf("%s: 坚持住，马上赶来救你!\n", getName().c_str());
 }
 // 获取物资方法get()
 void get(){
  printf("%s: 已收到，马上过来分享物资!\n", getName().c_str());
 }
};
#endif
/* AllyCenter.cpp */
#include "AllyCenter.h"
#include "Observer.h"
AllyCenter::AllyCenter(){
 printf("大吉大利，今晚吃鸡!\n");
}
// 加入玩家
void AllyCenter::join(Observer* player){
 if (playerList.size() == 4){
  printf("吃鸡玩家已满!\n");
  return;
 }
 printf("玩家 %s 正在加入中......\n", player->getName().c_str());
 playerList.push_back(player);
 if (playerList.size() == 4){
  printf("组队成功，马上开局!\n");
 }
}
// 剔除玩家
void AllyCenter::remove(Observer* player){
 printf("玩家%s退出房间\n", player->getName().c_str());
}
AllyCenterController::AllyCenterController(){
}
// 实现通知方法
void AllyCenterController::notify(INFO_TYPE infoType, std::string name){
 switch (infoType){
 case RESOURCE:
  for (Observer* obj : playerList){
   if (obj->getName() != name){
    ((Player*)obj)->get();
   }
  }
  break;
 case HELP:
  for (Observer* obj : playerList){
   if (obj->getName() != name){
    ((Player*)obj)->help();
   }
  }
  break;
 default:
  printf("Everything is ok!\n");
 }
}
/* main.cpp*/
#include "Observer.h"
#include "AllyCenter.h"
// 客户端程序
int main()
{
 // 创建一个战队
 AllyCenterController* controller = new AllyCenterController();
 // 创建4个吃鸡玩家，并加入战队
 Player* CurryCoder = new Player("CurryCoder");
 Player* Durant = new Player("Durant");
 Player* Harden = new Player("Harden");
 Player* James = new Player("James");
 controller->join(CurryCoder);
 controller->join(Durant);
 controller->join(Harden);
 controller->join(James);
 printf("\n\n");
 // CurryCoder发现物资，呼叫队友
 CurryCoder->call(RESOURCE, controller);
 printf("\n\n");
 // Durant需要求救
 Durant->call(HELP, controller);
 printf("\n\n");
 return 0;
}