装饰模式 HelloWorld
/**
* 定义一个基本装修接口
* @author admin
*
*/
public interface IDecorator {
/**
* 装修方法
*/
void decorate();
}
/**
* 装修基本类
* @author admin
*
*/
public class Decorator implements IDecorator{
/**
* 基本实现方法
*/
public void decorate() {
System.out.println("水电装修、天花板以及粉刷墙。。。");
}
}
/**
* 基本装饰类
* @author admin
*
*/
public abstract class BaseDecorator implements IDecorator{
private IDecorator decorator;
public BaseDecorator(IDecorator decorator) {
this.decorator = decorator;
}
/**
* 调用装饰方法
*/
public void decorate() {
if(decorator != null) {
decorator.decorate();
}
}
}
/**
* 窗帘装饰类
* @author admin
*
*/
public class CurtainDecorator extends BaseDecorator{
public CurtainDecorator(IDecorator decorator) {
super(decorator);
}
/**
* 窗帘具体装饰方法
*/
@Override
public void decorate() {
System.out.println("窗帘装饰。。。");
super.decorate();
}
}
public static void main( String[] args )
{
IDecorator decorator = new Decorator();
IDecorator curtainDecorator = new CurtainDecorator(decorator);
curtainDecorator.decorate();
}
运行结果
窗帘装饰。。。
水电装修、天花板以及粉刷墙。。。
通过这个案例，我们可以了解到：如果我们想要在基础类上添加新的装修功能，只需要基于抽象类 BaseDecorator 去实现继承类，通过构造函数调用父类，以及重写装修方法实现装修窗帘的功能即可。在 main 函数中，我们通过实例化装饰类，调用装修方法，即可在基础装修的前提下，获得窗帘装修功能。基于装饰器模式实现的装修功能的代码结构简洁易读，业务逻辑也非常清晰，并且如果我们需要扩展新的装修功能，只需要新增一个继承了抽象装饰类的子类即可。在这个案例中，我们仅实现了业务扩展功能，接下来，我将通过装饰器模式优化电商系统中的商品价格策略，实现不同促销活动的灵活组合。
装饰模式在电商价格策略中的应用
/**
* 主订单
* @author admin
*
*/
public class Order {
private int id; //订单ID
private String orderNo; //订单号
private BigDecimal totalPayMoney; //总支付金额
private List<OrderDetail> list; //详细订单列表
}
/**
* 详细订单
* @author admin
*
*/
public class OrderDetail {
private int id; //详细订单ID
private int orderId;//主订单ID
private Merchandise merchandise; //商品详情
private BigDecimal payMoney; //支付单价
}
/**
* 商品
* @author admin
*
*/
public class Merchandise {
private String sku;//商品SKU
private String name; //商品名称
private BigDecimal price; //商品单价
private Map<PromotionType, SupportPromotions> supportPromotions; //支持促销类型
}
/**
* 促销类型
* @author admin
*
*/
public class SupportPromotions implements Cloneable{
private int id;//该商品促销的ID
private PromotionType promotionType;//促销类型 1\优惠券 2\红包
private int priority; //优先级
private UserCoupon userCoupon; //用户领取该商品的优惠券
private UserRedPacket userRedPacket; //用户领取该商品的红包
//重写clone方法
public SupportPromotions clone(){
SupportPromotions supportPromotions = null;
try{
supportPromotions = (SupportPromotions)super.clone();
}catch(CloneNotSupportedException e){
e.printStackTrace();
}
return supportPromotions;
}
}
/**
* 优惠券
* @author admin
*
*/
public class UserCoupon {
private int id; //优惠券ID
private int userId; //领取优惠券用户ID
private String sku; //商品SKU
private BigDecimal coupon; //优惠金额
}
/**
* 红包
* @author admin
*
*/
public class UserRedPacket {
private int id; //红包ID
private int userId; //领取用户ID
private String sku; //商品SKU
private BigDecimal redPacket; //领取红包金额
}
/**
* 计算支付金额接口类
* @author admin
*
*/
public interface IBaseCount {
BigDecimal countPayMoney(OrderDetail orderDetail);
}
/**
* 支付基本类
* @author admin
*
*/
public class BaseCount implements IBaseCount{
public BigDecimal countPayMoney(OrderDetail orderDetail) {
orderDetail.setPayMoney(orderDetail.getMerchandise().getPrice());
System.out.println("商品原单价金额为：" + orderDetail.getPayMoney());
return orderDetail.getPayMoney();
}
}
/**
* 计算支付金额的抽象类
* @author admin
*
*/
public abstract class BaseCountDecorator implements IBaseCount{
private IBaseCount count;
public BaseCountDecorator(IBaseCount count) {
this.count = count;
}
public BigDecimal countPayMoney(OrderDetail orderDetail) {
BigDecimal payTotalMoney = new BigDecimal(0);
if(count!=null) {
payTotalMoney = count.countPayMoney(orderDetail);
}
return payTotalMoney;
}
}
/**
* 计算使用优惠券后的金额
* @author admin
*
*/
public class CouponDecorator extends BaseCountDecorator{
public CouponDecorator(IBaseCount count) {
super(count);
}
public BigDecimal countPayMoney(OrderDetail orderDetail) {
BigDecimal payTotalMoney = new BigDecimal(0);
payTotalMoney = super.countPayMoney(orderDetail);
payTotalMoney = countCouponPayMoney(orderDetail);
return payTotalMoney;
}
private BigDecimal countCouponPayMoney(OrderDetail orderDetail) {
BigDecimal coupon = orderDetail.getMerchandise().getSupportPromotions().get(PromotionType.COUPON).getUserCoupon().getCoupon();
System.out.println("优惠券金额：" + coupon);
orderDetail.setPayMoney(orderDetail.getPayMoney().subtract(coupon));
return orderDetail.getPayMoney();
}
}
/**
* 计算使用红包后的金额
* @author admin
*
*/
public class RedPacketDecorator extends BaseCountDecorator{
public RedPacketDecorator(IBaseCount count) {
super(count);
}
public BigDecimal countPayMoney(OrderDetail orderDetail) {
BigDecimal payTotalMoney = new BigDecimal(0);
payTotalMoney = super.countPayMoney(orderDetail);
payTotalMoney = countCouponPayMoney(orderDetail);
return payTotalMoney;
}
private BigDecimal countCouponPayMoney(OrderDetail orderDetail) {
BigDecimal redPacket = orderDetail.getMerchandise().getSupportPromotions().get(PromotionType.REDPACKED).getUserRedPacket().getRedPacket();
System.out.println("红包优惠金额：" + redPacket);
orderDetail.setPayMoney(orderDetail.getPayMoney().subtract(redPacket));
return orderDetail.getPayMoney();
}
}
/**
* 计算促销后的支付价格
* @author admin
*
*/
public class PromotionFactory {
public static BigDecimal getPayMoney(OrderDetail orderDetail) {
//获取给商品设定的促销类型
Map<PromotionType, SupportPromotions> supportPromotionslist = orderDetail.getMerchandise().getSupportPromotions();
//初始化计算类
IBaseCount baseCount = new BaseCount();
if(supportPromotionslist!=null && supportPromotionslist.size()>0) {
for(PromotionType promotionType: supportPromotionslist.keySet()) {//遍历设置的促销类型，通过装饰器组合促销类型
baseCount = protmotion(supportPromotionslist.get(promotionType), baseCount);
}
}
return baseCount.countPayMoney(orderDetail);
}
/**
* 组合促销类型
* @param supportPromotions
* @param baseCount
* @return
*/
private static IBaseCount protmotion(SupportPromotions supportPromotions, IBaseCount baseCount) {
if(supportPromotions.getPromotionType()==PromotionType.COUPON) {
baseCount = new CouponDecorator(baseCount);
}else if(supportPromotions.getPromotionType()==PromotionType.REDPACKED) {
baseCount = new RedPacketDecorator(baseCount);
}
return baseCount;
}
}
public static void main( String[] args ) throws InterruptedException, IOException
{
Order order = new Order();
init(order);
for(OrderDetail orderDetail: order.getList()) {
BigDecimal payMoney = PromotionFactory.getPayMoney(orderDetail);
orderDetail.setPayMoney(payMoney);
System.out.println("最终支付金额：" + orderDetail.getPayMoney());
}
}
