命令模式将请求以命令的形式包裹在对象中，然后传递给调用者，调用者寻找处理该命令的对象，并执行命令。

 

 

真正的命令执行对象 

Stock

public class Stock {    
    private String name = "ABC";
    private int quantity = 10;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getQuantity() {
        return quantity;
    }
    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }
    
    public void buyStock() {
        System.out.println("BuyStock [name=" + name + ", quantity=" + quantity + "]");
    }
    public void sellStock() {
        System.out.println("SellStock [name=" + name + ", quantity=" + quantity + "]");
    }
    
    
}

 

 

Command接口

public interface Order {
    public void execute();
}

 

 

Command接口的实现者，用来执行具体的命令。

 

BuyStock 

public class BuyStock implements Order{
    private Stock abcStock;
    
    
    
    public BuyStock(Stock abcStock) {
        super();
        this.abcStock = abcStock;
    }

    @Override
    public void execute() {
        // TODO Auto-generated method stub
        abcStock.buyStock();
    }
}

 

 SellStock

public class SellStock implements Order{
private Stock abcStock;
    
    public SellStock(Stock abcStock) {
        super();
        this.abcStock = abcStock;
    }
    @Override
    public void execute() {
        // TODO Auto-generated method stub
        abcStock.sellStock();
    }

}

 

 

命令的请求者，是命令模式中最重要的角色。这个角色用来对各个命令进行控制。

Broker

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 placeOrderList() {
        for(Order order: orderList) {
            order.execute();
        }
        orderList.clear();
    }
}

 

Main

public class Main {
    public static void main(String[] args) {
        Stock abc = new Stock();
        
        Order buyAbc = new BuyStock(abc);
        Order sellAbc = new SellStock(abc);
        
        Broker broker = new Broker();
        
        broker.takeOrder(buyAbc);
        broker.takeOrder(sellAbc);
        
        broker.placeOrderList();
    }
}

运行结果：
BuyStock [name=ABC, quantity=10]
SellStock [name=ABC, quantity=10]

 

 

 

参考资料：

https://www.runoob.com/design-pattern/command-pattern.html