java 篇 1.基础地基 2.设计原理 3.项目实战这章功力有点不足了先放放改日再会会。定义优惠券规则业务流程分析及实现优惠规则策略模式导包定义接口因为是给其他服务用的那得放在 api 模块下和下面 FallbackConfig 当中对应优惠券方案推荐 ComplateFuture 并发运算添加线程池筛选最优解核心代码package com.tianji.promotion.service.impl; import com.tianji.api.dto.promotion.CouponDiscountDTO; import com.tianji.api.dto.promotion.OrderCouponDTO; import com.tianji.api.dto.promotion.OrderCourseDTO; import com.tianji.common.utils.CollUtils; import com.tianji.common.utils.UserContext; import com.tianji.promotion.domain.po.Coupon; import com.tianji.promotion.domain.po.CouponScope; import com.tianji.promotion.enums.UserCouponStatus; import com.tianji.promotion.mapper.UserCouponMapper; import com.tianji.promotion.service.ICouponScopeService; import com.tianji.promotion.service.IDiscountService; import com.tianji.promotion.strategy.discount.Discount; import com.tianji.promotion.strategy.discount.DiscountStrategy; import com.tianji.promotion.utils.PermuteUtil; import lombok.RequiredArgsConstructor; import lombok.extern.slf4j.Slf4j; import org.springframework.stereotype.Service; import java.util.*; import java.util.concurrent.CompletableFuture; import java.util.concurrent.CountDownLatch; import java.util.concurrent.Executor; import java.util.concurrent.TimeUnit; import java.util.stream.Collectors; Slf4j Service RequiredArgsConstructor public class DiscountServiceImpl implements IDiscountService { private final UserCouponMapper userCouponMapper; private final ICouponScopeService scopeService; private final Executor discountSolutionExecutor; Override public ListCouponDiscountDTO findDiscountSolution(ListOrderCourseDTO orderCourses) { // 1.查询我的所有可用优惠券 ListCoupon coupons userCouponMapper.queryMyCoupons(UserContext._getUser_()); if (CollUtils._isEmpty_(coupons)) { return CollUtils._emptyList_(); } // 2.初筛 // 2.1.计算订单总价 int totalAmount orderCourses.stream().mapToInt(OrderCourseDTO::getPrice).sum(); // 2.2.筛选可用券 ListCoupon availableCoupons coupons.stream() .filter(c - DiscountStrategy._getDiscount_(c.getDiscountType()).canUse(totalAmount, c)) .collect(Collectors._toList_()); if (CollUtils._isEmpty_(availableCoupons)) { return CollUtils._emptyList_(); } // 3.排列组合出所有方案 // 3.1.细筛找出每一个优惠券的可用的课程判断课程总价是否达到优惠券的使用需求 MapCoupon, ListOrderCourseDTO availableCouponMap findAvailableCoupon(availableCoupons, orderCourses); if (CollUtils._isEmpty_(availableCouponMap)) { return CollUtils._emptyList_(); } // 3.2.排列组合 availableCoupons new ArrayList(availableCouponMap.keySet()); ListListCoupon solutions PermuteUtil._permute_(availableCoupons); // 3.3.添加单券的方案 for (Coupon c : availableCoupons) { solutions.add(List._of_(c)); } // 4.计算方案的优惠明细 ListCouponDiscountDTO list Collections._synchronizedList_(new ArrayList(solutions.size())); // 4.1.定义闭锁 CountDownLatch latch new CountDownLatch(solutions.size()); for (ListCoupon solution : solutions) { // 4.2.异步计算 CompletableFuture ._supplyAsync_( () - calculateSolutionDiscount(availableCouponMap, orderCourses, solution), discountSolutionExecutor ).thenAccept(dto - { // 4.3.提交任务结果 list.add(dto); latch.countDown(); }); } // 4.4.等待运算结束 try { latch.await(1, TimeUnit._SECONDS_); } catch (InterruptedException e) { _log_.error(优惠方案计算被中断{}, e.getMessage()); } // 5.筛选最优解 return findBestSolution(list); } Override public CouponDiscountDTO queryDiscountDetailByOrder(OrderCouponDTO orderCouponDTO) { // 1.查询用户优惠券 ListLong userCouponIds orderCouponDTO.getUserCouponIds(); ListCoupon coupons userCouponMapper.queryCouponByUserCouponIds(userCouponIds, UserCouponStatus._UNUSED_); if (CollUtils._isEmpty_(coupons)) { return null; } // 2.查询优惠券对应课程 MapCoupon, ListOrderCourseDTO availableCouponMap findAvailableCoupon(coupons, orderCouponDTO.getCourseList()); if (CollUtils._isEmpty_(availableCouponMap)) { return null; } // 3.查询优惠券规则 return calculateSolutionDiscount(availableCouponMap, orderCouponDTO.getCourseList(), coupons); } private ListCouponDiscountDTO findBestSolution(ListCouponDiscountDTO list) { // 1.准备Map记录最优解 MapString, CouponDiscountDTO moreDiscountMap new HashMap(); MapInteger, CouponDiscountDTO lessCouponMap new HashMap(); // 2.遍历筛选最优解 for (CouponDiscountDTO solution : list) { // 2.1.计算当前方案的id组合 String ids solution.getIds().stream() .sorted(Long::_compare_).map(String::_valueOf_).collect(Collectors._joining_(,)); // 2.2.比较用券相同时优惠金额是否最大 CouponDiscountDTO best moreDiscountMap.get(ids); if (best ! null best.getDiscountAmount() solution.getDiscountAmount()) { // 当前方案优惠金额少跳过 continue; } // 2.3.比较金额相同时用券数量是否最少 best lessCouponMap.get(solution.getDiscountAmount()); int size solution.getIds().size(); if (size 1 best ! null best.getIds().size() size) { // 当前方案用券更多放弃 continue; } // 2.4.更新最优解 moreDiscountMap.put(ids, solution); lessCouponMap.put(solution.getDiscountAmount(), solution); } // 3.求交集 CollectionCouponDiscountDTO bestSolutions CollUtils ._intersection_(moreDiscountMap.values(), lessCouponMap.values()); // 4.排序按优惠金额降序 return bestSolutions.stream() .sorted(Comparator._comparingInt_(CouponDiscountDTO::getDiscountAmount).reversed()) .collect(Collectors._toList_()); } private CouponDiscountDTO calculateSolutionDiscount( MapCoupon, ListOrderCourseDTO couponMap, ListOrderCourseDTO courses, ListCoupon solution) { // 1.初始化DTO CouponDiscountDTO dto new CouponDiscountDTO(); // 2.初始化折扣明细的映射 MapLong, Integer detailMap courses.stream().collect(Collectors._toMap_(OrderCourseDTO::getId, oc - 0)); dto.setDiscountDetail(detailMap); // 3.计算折扣 for (Coupon coupon : solution) { // 3.1.获取优惠券限定范围对应的课程 ListOrderCourseDTO availableCourses couponMap.get(coupon); // 3.2.计算课程总价(课程原价 - 折扣明细) int totalAmount availableCourses.stream() .mapToInt(oc - oc.getPrice() - detailMap.get(oc.getId())).sum(); // 3.3.判断是否可用 Discount discount DiscountStrategy._getDiscount_(coupon.getDiscountType()); if (!discount.canUse(totalAmount, coupon)) { // 券不可用跳过 continue; } // 3.4.计算优惠金额 int discountAmount discount.calculateDiscount(totalAmount, coupon); // 3.5.计算优惠明细 calculateDiscountDetails(detailMap, availableCourses, totalAmount, discountAmount); // 3.6.更新DTO数据 dto.getIds().add(coupon.getCreater()); dto.getRules().add(discount.getRule(coupon)); dto.setDiscountAmount(discountAmount dto.getDiscountAmount()); } return dto; } private void calculateDiscountDetails(MapLong, Integer detailMap, ListOrderCourseDTO courses, int totalAmount, int discountAmount) { int times 0; int remainDiscount discountAmount; for (OrderCourseDTO course : courses) { // 更新课程已计算数量 times; int discount 0; // 判断是否是最后一个课程 if (times courses.size()) { // 是最后一个课程总折扣金额 - 之前所有商品的折扣金额之和 discount remainDiscount; } else { // 计算折扣明细课程价格在总价中占的比例乘以总的折扣 discount discountAmount * course.getPrice() / totalAmount; remainDiscount - discount; } // 更新折扣明细 detailMap.put(course.getId(), discount detailMap.get(course.getId())); } } private MapCoupon, ListOrderCourseDTO findAvailableCoupon( ListCoupon coupons, ListOrderCourseDTO courses) { MapCoupon, ListOrderCourseDTO map new HashMap(coupons.size()); for (Coupon coupon : coupons) { // 1.找出优惠券的可用的课程 ListOrderCourseDTO availableCourses courses; if (coupon.getSpecific()) { // 1.1.限定了范围查询券的可用范围 ListCouponScope scopes scopeService.lambdaQuery().eq(CouponScope::getCouponId, coupon.getId()).list(); // 1.2.获取范围对应的分类id SetLong scopeIds scopes.stream().map(CouponScope::getBizId).collect(Collectors._toSet_()); // 1.3.筛选课程 availableCourses courses.stream() .filter(c - scopeIds.contains(c.getCateId())).collect(Collectors._toList_()); } if (CollUtils._isEmpty_(availableCourses)) { // 没有任何可用课程抛弃 continue; } // 2.计算课程总价 int totalAmount availableCourses.stream().mapToInt(OrderCourseDTO::getPrice).sum(); // 3.判断是否可用 Discount discount DiscountStrategy._getDiscount_(coupon.getDiscountType()); if (discount.canUse(totalAmount, coupon)) { map.put(coupon, availableCourses); } } return map; } }至此天机学堂篇完结能看到这里的你已经超厉害了如果对你有帮助的话请点赞关注收藏。热爱可抵一切 ❤️