Spring Boot整合Drools规则引擎实战指南

组件	作用
KieContainer	规则容器，管理KieBase生命周期
KieSession	规则执行会话，分为有状态和无状态
Fact	传入规则引擎的Java对象
Rule	使用DRL编写的业务规则

二、Spring Boot集成Drools

2.1 环境准备

Maven依赖配置：

XML 复制代码

<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>

2.2 配置类编写

java 复制代码

@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();
    }
}

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三、规则开发实战

3.1 DRL规则文件示例

src/main/resources/rules/discount.drl：

java 复制代码

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 // 规则优先级
    when
        $order : Order(holidayPromotion == true)
    then
        $order.setDiscount(0.20);
        System.out.println("Applied holiday 20% discount");
end

四、服务层集成

4.1 规则执行服务

java 复制代码

@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;
    }
}

4.2 业务逻辑调用

java 复制代码

@RestController
@RequestMapping("/orders")
public class OrderController {

    @Autowired
    private RuleEngineService ruleEngine;

    @PostMapping("/process")
    public Order processOrder(@RequestBody Order order) {
        ruleEngine.executeRules(order);
        return order;
    }
}

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五、测试与验证

5.1 单元测试

java 复制代码

@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);
    }
}

5.2 效果验证

请求示例：

java 复制代码

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

响应结果：

java 复制代码

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

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六、高级配置与优化

6.1 动态规则更新

java 复制代码

@Autowired
private KieContainer kieContainer;

public void reloadRules() {
    kieContainer.updateToVersion(kieContainer.getReleaseId());
}

6.2 性能优化建议

使用无状态会话：适用于无会话状态的规则执行

预编译规则：KieBase缓存优化

合理设计规则条件：复杂条件放在规则左侧(LHS)前面

限制规则数量：单个KieBase建议不超过1000条规则

七、常见问题排查

问题现象	可能原因	解决方案
规则未触发	事实对象未正确插入	检查kieSession.insert()调用
规则执行顺序错误	缺少salience优先级设置	为规则添加salience属性
内存溢出	有状态会话未及时释放	确保finally块中调用dispose()
规则加载失败	DRL语法错误	检查控制台错误日志

八、最佳实践总结

规则与业务代码分离：将DRL文件存放在独立resources/rules目录

版本控制规则文件：使用Git管理规则变更历史

监控规则执行：集成Micrometer监控指标

单元测试覆盖率：为关键规则编写测试用例

避免过度复杂规则：单个规则条件不超过5个