设计模式-命令模式

请求以命令的形式包裹在对象中，并传给调用对象。调用对象寻找可以处理该命令的合适的对象，并把该命令传给相应的对象，该对象执行命令

命令模式

//知道如何实施与执行一个与请求相关的操作，任何类都可能作为一个接受者
class Receiver
{
    public void Action()
    {
        Console.WriteLine("执行请求");
    }
}
//Command 执行操作的接口
abstract class Command
{
    protected Receiver receiver;
    public Command(Receiver receiver)
    {
        this.receiver = receiver;
    }
    public abstract void Execute();
}
//ConcreateCommand 将一个接受者对象绑定于一个动作，调用接受者相应的操作，以实现Execute
class ConcreateCommand : Command
{
    public ConcreateCommand(Receiver receiver) : base(receiver)
    {}
    public override void Execute()
    {
        receiver.Action();
    }
}
//Invoker 要求命令执行请求
class Invoker
{
    private Command command;
    public void SetCommand(Command command)
    {
        this.command = command;
    }
    public void ExecuteCommand()
    {
        command.Execute();
    }
}
//Client
Receiver rec = new Receiver();
Command co = new ConcreateCommand(rec);
Invoker i = new Invoker();

i.SetCommand(co);
i.ExecuteCommand();

//命令接口
public interface Order {
   void execute();
}
//请求类
public class Stock {
   
   private String name = "ABC";
   private int quantity = 10;
 
   public void buy(){
      System.out.println("Stock [ Name: "+name+", 
         Quantity: " + quantity +" ] bought");
   }
   public void sell(){
      System.out.println("Stock [ Name: "+name+", 
         Quantity: " + quantity +" ] sold");
   }
}
//实现命令接口
public class BuyStock implements Order {
   private Stock abcStock;
 
   public BuyStock(Stock abcStock){
      this.abcStock = abcStock;
   }
 
   public void execute() {
      abcStock.buy();
   }
}
public class SellStock implements Order {
   private Stock abcStock;
 
   public SellStock(Stock abcStock){
      this.abcStock = abcStock;
   }
 
   public void execute() {
      abcStock.sell();
   }
}
//命令调用类
import java.util.ArrayList;
import java.util.List;
 
public class Broker {
   private List<Order> orderList = new ArrayList<Order>(); 
 
   public void takeOrder(Order order){
      orderList.add(order);      
   }
 
   public void placeOrders(){
      for (Order order : orderList) {
         order.execute();
      }
      orderList.clear();
   }
}
//Client
public class CommandPatternDemo {
   public static void main(String[] args) {
      Stock abcStock = new Stock();
 
      BuyStock buyStockOrder = new BuyStock(abcStock);
      SellStock sellStockOrder = new SellStock(abcStock);
 
      Broker broker = new Broker();
      broker.takeOrder(buyStockOrder);
      broker.takeOrder(sellStockOrder);
 
      broker.placeOrders();
   }
}
/*
Stock [ Name: ABC, Quantity: 10 ] bought
Stock [ Name: ABC, Quantity: 10 ] sold
*/