设计模式21 - 中介者模式【【Mediator Pattern】

public abstract class AbstractMediator { 
    protected Purchase purchase; 
    protected Sale sale; 
    protected Stock stock; 
    //构造函数
    public AbstractMediator(){ 
         purchase = new Purchase(this); 
         sale = new Sale(this); 
         stock = new Stock(this); 
    } 
    //中介者最重要的方法，叫做事件方法，处理多个对象之间的关系
    public abstract void execute(String str,Object...objects); 
}
------------------------------------------------------------------------
public class Mediator extends AbstractMediator { 
    //中介者最重要的方法
    public void execute(String str,Object...objects){ 
         if(str.equals("purchase.buy")){ //采购电脑
             this.buyComputer((Integer)objects[0]); 
         }else if(str.equals("sale.sell")){ //销售电脑
             this.sellComputer((Integer)objects[0]); 
         }else if(str.equals("sale.offsell")){ //折价销售
             this.offSell(); 
         }else if(str.equals("stock.clear")){ //清仓处理
             this.clearStock(); 
         } 
     } 
    //采购电脑
    private void buyComputer(int number){ 
         int saleStatus = super.sale.getSaleStatus(); 
         if(saleStatus>80){ //销售情况良好
             System.out.println("采购IBM电脑:"+number + "台"); 
             super.stock.increase(number); 
         }else{ //销售情况不好
             int buyNumber = number/2; //折半采购
             System.out.println("采购IBM电脑："+buyNumber+ "台"); 
         } 
    } 
    //销售电脑
    private void sellComputer(int number){ 
         if(super.stock.getStockNumber()<number){ //库存数量不够销售
             super.purchase.buyIBMcomputer(number); 
         } 
             super.stock.decrease(number); 
     } 
    //折价销售电脑
    private void offSell(){ 
         System.out.println("折价销售IBM电脑"+stock.getStockNumber()+"台"); 
     } 
    //清仓处理
    private void clearStock(){ 
         //要求清仓销售
         super.sale.offSale(); 
         //要求采购人员不要采购
         super.purchase.refuseBuyIBM(); 
     } 
} 
------------------------------------------------------------------
public abstract class AbstractColleague { 
    protected AbstractMediator mediator; 
    public AbstractColleague(AbstractMediator _mediator){ 
         this.mediator = _mediator; 
     } 
} 
public class Purchase extends AbstractColleague{ 
    public Purchase(AbstractMediator _mediator){ 
      super(_mediator); 
    } 
   //采购IBM型号的电脑
   public void buyIBMcomputer(int number){ 
       super.mediator.execute("purchase.buy", number); 
  } 
  //不在采购IBM电脑
   public void refuseBuyIBM(){ 
       System.out.println("不再采购IBM电脑"); 
   } 
} 
-----------------------------------------------------------------
public class Stock extends AbstractColleague { 
    public Stock(AbstractMediator _mediator){ 
      super(_mediator); 
    } 
    //刚开始有100台电脑
    private static int COMPUTER_NUMBER =100; 
    //库存增加
    public void increase(int number){ 
          COMPUTER_NUMBER = COMPUTER_NUMBER + number; 
          System.out.println("库存数量为："+COMPUTER_NUMBER); 
     } 
    //库存降低
    public void decrease(int number){ 
          COMPUTER_NUMBER = COMPUTER_NUMBER - number; 
          System.out.println("库存数量为："+COMPUTER_NUMBER); 
      } 
    //获得库存数量
    public int getStockNumber(){ 
          return COMPUTER_NUMBER; 
      } 
    //存货压力大了，就要通知采购人员不要采购，销售人员要尽快销售
    public void clearStock(){ 
          System.out.println("清理存货数量为："+COMPUTER_NUMBER); 
          super.mediator.execute("stock.clear"); 
  } 
} 
--------------------------------------------------------------------
public class Sale extends AbstractColleague { 
    public Sale(AbstractMediator _mediator){ 
         super(_mediator); 
     } 
    //销售IBM型号的电脑
    public void sellIBMComputer(int number){ 
         super.mediator.execute("sale.sell", number); 
         System.out.println("销售IBM电脑"+number+"台"); 
    } 
    //反馈销售情况,0——100之间变化，0代表根本就没人卖，100代表非常畅销，出1一个卖一个
    public int getSaleStatus(){ 
         Random rand = new Random(System.currentTimeMillis()); 
         int saleStatus = rand.nextInt(100); 
         System.out.println("IBM电脑的销售情况为："+saleStatus); 
         return saleStatus; 
     } 
    //折价处理
    public void offSale(){ 
         super.mediator.execute("sale.offsell"); 
    } 
} 
-------------------------------------------------------------------
public class Client { 
    public static void main(String[] args) { 
          AbstractMediator mediator = new Mediator(); 
          //采购人员采购电脑
          System.out.println("------采购人员采购电脑--------"); 
          Purchase purchase = new Purchase(mediator); 
          purchase.buyIBMcomputer(100); 
          //销售人员销售电脑
          System.out.println("\n------销售人员销售电脑--------"); 
          Sale sale = new Sale(mediator); 
          sale.sellIBMComputer(1); 
          //库房管理人员管理库存
          System.out.println("\n------库房管理人员清库处理--------") Stock stock = new Stock(mediator); 
          stock.clearStock(); 
  } 
}