Java策略模式实现简单购物车功能

package com.journaldev.design.strategy;
public interface PaymentStrategy {
	public void pay(int amount);
}

package com.journaldev.design.strategy;

public class CreditCardStrategy implements PaymentStrategy {

	private String name;
	private String cardNumber;
	private String cvv;
	private String dateOfExpiry;

	public CreditCardStrategy(String nm, String ccNum, String cvv, String expiryDate){
		this.name=nm;
		this.cardNumber=ccNum;
		this.cvv=cvv;
		this.dateOfExpiry=expiryDate;
	}
	@Override
	public void pay(int amount) {
		System.out.println(amount +" paid with credit/debit card");
	}

}

package com.journaldev.design.strategy;

public class Item {

	private String upcCode;
	private int price;

	public Item(String upc, int cost){
		this.upcCode=upc;
		this.price=cost;
	}

	public String getUpcCode() {
		return upcCode;
	}

	public int getPrice() {
		return price;
	}

}

package com.journaldev.design.strategy;

import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;

public class ShoppingCart {

	//List of items
	List<Item> items;

	public ShoppingCart(){
		this.items=new ArrayList<Item>();
	}

	public void addItem(Item item){
		this.items.add(item);
	}

	public void removeItem(Item item){
		this.items.remove(item);
	}

	public int calculateTotal(){
		int sum = 0;
		for(Item item : items){
			sum += item.getPrice();
		}
		return sum;
	}

	public void pay(PaymentStrategy paymentMethod){
		int amount = calculateTotal();
		paymentMethod.pay(amount);
	}
}

package com.journaldev.design.strategy;

public class ShoppingCartTest {

	public static void main(String[] args) {
		ShoppingCart cart = new ShoppingCart();

		Item item1 = new Item("1234",10);
		Item item2 = new Item("5678",40);

		cart.addItem(item1);
		cart.addItem(item2);

		//pay by paypal
		cart.pay(new PaypalStrategy("myemail@example.com", "mypwd"));

		//pay by credit card
		cart.pay(new CreditCardStrategy("Pankaj Kumar", "1234567890123456", "786", "12/15"));
	}

}