优惠券使用规则引擎来计算优惠 (drools)

rule rule001
when
	条件
then
	执行结果
end

    private static Resource[] getRuleFiles() throws IOException {
        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        return resourcePatternResolver.getResources("classpath*:rules/"  + "**/*.drl");
    }

    private static KieSession getSession() throws Exception {
        KieServices kieServices = KieServices.Factory.get();
        KieFileSystem kfs = kieServices.newKieFileSystem();

        for (Resource file : getRuleFiles()) {
            log.info("rule file: " + file.getFilename());
            try {
                kfs.write(ResourceFactory.newClassPathResource("rules/" + file.getFilename(), "UTF-8"));
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        KieBuilder kieBuilder = kieServices.newKieBuilder(kfs).buildAll();
        Results results = kieBuilder.getResults();
        if (results.hasMessages(Message.Level.ERROR)) {
            for (Message msg : results.getMessages()) {
                log.error("drools script error info : " + msg.getText());
            }
            throw new Exception("drools script error");
        }
        return kieServices.newKieContainer(KieServices.Factory.get().getRepository().getDefaultReleaseId()).newKieSession();
	}

        KieSession kieSession = getSession();
        kieSession.insert(order);
        kieSession.insert(coupon);
        kieSession.insert(result);
        int hit = kieSession.fireAllRules(); // hit 是所有规则被命中的规则数

package com.mall.coupon.drools.rules;

// 折扣型

import com.mall.coupon.drools.model.Coupon
import com.mall.coupon.drools.model.Order
import com.mall.coupon.drools.model.OrderItem
import com.mall.coupon.drools.model.EnquiryResult

global com.mall.coupon.drools.service.CouponBatchService couponBatchService
global com.mall.coupon.drools.service.UserCouponService userCouponService
//global com.mall.coupon.drools.service.UserCouponService userCouponService
global com.mall.coupon.drools.service.UserService userService

// 折扣类优惠券

// order 对整个订单打折
rule "rule-discount-order"
when
    $result: EnquiryResult()
    $order: Order()
    $coupon: Coupon(couponType == "5" && subCouponType == "1" &&
        (minBuyAmount == 0 || $order.totalAmount >= minBuyAmount))
then
    System.out.println("命中 discount-order");
    $result.setTotalDiscount($order.getTotalAmount() * $coupon.getNominal() / 100);
end


// sku 对特定的sku商品打折
rule "rule-discount-sku"
when
    $item: OrderItem()
    $result: EnquiryResult()
    $coupon: Coupon(couponType == "5" && subCouponType == "2" &&
        (minBuyAmount == 0 || $item.totalAmount >= minBuyAmount) &&
        couponBatchService.skuUsable($coupon.getCouponBatchCode(), $item.getProductSkuId()))
then
    System.out.println("coupon code: " + $coupon.getCouponBatchCode());
    System.out.println("couponBatchService: " + couponBatchService);
    System.out.println("命中 discount-sku");
    $result.setTotalDiscount($item.getTotalAmount() * (100 - $coupon.getNominal()) / 100);
end