<dependency>
    <groupId>org.drools</groupId>
    <artifactId>drools-core</artifactId>
    <version>7.73.0.Final</version>
</dependency>
<dependency>
    <groupId>org.drools</groupId>
    <artifactId>drools-compiler</artifactId>
    <version>7.73.0.Final</version>
</dependency>
<dependency>
    <groupId>org.kie</groupId>
    <artifactId>kie-spring</artifactId>
    <version>7.73.0.Final</version>
</dependency>

@Configuration
public class DroolsConfig {
    private static final String RULES_PATH = "rules/";
    @Bean
    public KieFileSystem kieFileSystem() throws IOException {
        KieFileSystem kieFileSystem = getKieServices().newKieFileSystem();
        for (Resource file : getRuleFiles()) {
            kieFileSystem.write(ResourceFactory.newClassPathResource(RULES_PATH + file.getFilename(), "UTF-8"));
        }
        return kieFileSystem;
    }
    private Resource[] getRuleFiles() throws IOException {
        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        return resourcePatternResolver.getResources("classpath*:" + RULES_PATH + "**/*.*");
    }
    @Bean
    public KieContainer kieContainer() throws IOException {
        KieServices kieServices = getKieServices();
        KieRepository kieRepository = kieServices.getRepository();
        kieRepository.addKieModule(kieRepository::getDefaultReleaseId);
        KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem());
        kieBuilder.buildAll();
        return kieServices.newKieContainer(kieRepository.getDefaultReleaseId());
    }
    private KieServices getKieServices() {
        return KieServices.Factory.get();
    }
}

package com.example.rules
import com.example.model.Order
rule "VIP Customer Discount"
    when
        $order : Order(customer.vipLevel >= 3, amount > 1000)
    then
        $order.setDiscount(0.15);
        System.out.println("Applied VIP 15% discount");
end
rule "Holiday Sale Discount"
    salience 10 // 規(guī)則優(yōu)先級
    when
        $order : Order(holidayPromotion == true)
    then
        $order.setDiscount(0.20);
        System.out.println("Applied holiday 20% discount");
end

@Service
public class RuleEngineService {
    @Autowired
    private KieContainer kieContainer;
    public void executeRules(Object fact) {
        KieSession kieSession = kieContainer.newKieSession();
        try {
            kieSession.insert(fact);
            kieSession.fireAllRules();
        } finally {
            kieSession.dispose();
        }
    }
    public <T> T executeStatelessRules(T fact) {
        StatelessKieSession statelessKieSession = kieContainer.newStatelessKieSession();
        statelessKieSession.execute(fact);
        return fact;
    }
}

@RestController
@RequestMapping("/orders")
public class OrderController {
    @Autowired
    private RuleEngineService ruleEngine;
    @PostMapping("/process")
    public Order processOrder(@RequestBody Order order) {
        ruleEngine.executeRules(order);
        return order;
    }
}

@SpringBootTest
class DroolsApplicationTests {
    @Autowired
    private RuleEngineService ruleEngine;
    @Test
    void testVipDiscount() {
        Customer vip = new Customer().setVipLevel(3);
        Order order = new Order(vip, 1500.0);
        ruleEngine.executeRules(order);
        assertEquals(0.15, order.getDiscount(), 0.001);
    }
}

POST /orders/process
{
    "customer": {
        "vipLevel": 3
    },
    "amount": 1500.0
}

{
    "discount": 0.15,
    "finalAmount": 1275.0
}

@Autowired
private KieContainer kieContainer;
public void reloadRules() {
    kieContainer.updateToVersion(kieContainer.getReleaseId());
}