Java策略模式的使用（枚举策略与简单工厂策略）

package com.amg.strategy.constants; import com.amg.strategy.vo.NewStrategyRequestVO; import com.amg.strategy.vo.NewStrategyResponseVO; import java.math.BigDecimal; import java.math.RoundingMode; import java.util.ArrayList; import java.util.Arrays; import java.util.List; /** * 枚举策略的实现 * @author Amg * @date 2021/12/2 */ public enum SelectStrategyEnum { /** * 原价 */ NORMAL(1,"原价策略") { @Override protected double payMoney(double money) { return money; } @Override protected List<String> getFoods(String... foods) { return Arrays.asList(foods); } }, COUPON(2,"优惠券满减策略") { @Override protected double payMoney(double money) { final Double thresholdPrice = requestVO.getThresholdPrice(); return money > thresholdPrice ? money - requestVO.getReducePrice() : money; } @Override protected List<String> getFoods(String... foods) { return Arrays.asList(foods); } }, DISCOUNT(3,"折扣策略") { @Override protected double payMoney(double money) { return BigDecimal.valueOf(money * requestVO.getDiscount()).setScale(2, RoundingMode.HALF_DOWN).doubleValue(); } @Override protected List<String> getFoods(String... foods) { return Arrays.asList(foods); } }, BUY_ONE_GET_ONE(4,"买一送一策略") { @Override protected double payMoney(double money) { return money; } @Override protected List<String> getFoods(String... foods) { List<String> list = new ArrayList<>(); StringBuilder sb = new StringBuilder(); for (String food : foods) { sb.append(food).append("*2").append(";"); } list.add(sb.toString()); return list; } }, FREE(5,"免费送策略") { @Override protected double payMoney(double money) { return 0; } @Override protected List<String> getFoods(String... foods) { return Arrays.asList(foods); } }; /** * 策略类型 */ private Integer type; /** * 策略名称 */ private String name; /** * 策略请求对象 */ private static NewStrategyRequestVO requestVO; private static void setRequestVO(NewStrategyRequestVO requestVO) { SelectStrategyEnum.requestVO = requestVO; } SelectStrategyEnum(Integer type, String name) { this.type = type; this.name = name; } /** * 最终要支付多少钱 * @param money 原始金额 * @return 最终要付的金额 */ protected abstract double payMoney(double money); /** * 最终能拿到的食物列表 * @param foods 食物列表 * @return 最终能拿到的食物列表 */ protected abstract List<String> getFoods(String... foods); /** * * @param requestVO 策略请求对象 * @return NewStrategyResponseVO */ public static NewStrategyResponseVO payAndShowFoods(NewStrategyRequestVO requestVO) { //调用时，将策略请求对象设置进去，以便各个成员使用 setRequestVO(requestVO); NewStrategyResponseVO responseVO = new NewStrategyResponseVO(); //遍历寻找匹配的策略 for (SelectStrategyEnum eachStrategy : SelectStrategyEnum.values()) { //匹配上之后，调用对应策略的具体实现 if (eachStrategy.type.equals(requestVO.getType())) { responseVO.setActualPayMoney(eachStrategy.payMoney(requestVO.getPayMoney())); responseVO.setActualFoods(eachStrategy.getFoods(requestVO.getFoods()).toString()); break; } } responseVO.setPayMoney(requestVO.getPayMoney()); responseVO.setFoods(Arrays.asList(requestVO.getFoods()).toString()); return responseVO; } }