第二步：创建/resources/application.yml文件

server:
  port: 8080
spring:
  application:
    name: drools_springboot

第三步：创建规则文件/resources/rules/helloworld.drl

package helloworld
rule "rule_helloworld"
    when
        eva l(true)
    then
        System.out.println("规则：rule_helloworld触发...");
end

第四步：编写配置类DroolsConfig

package com.itheima.drools.config;
import org.kie.api.KieBase;
import org.kie.api.KieServices;
import org.kie.api.builder.KieBuilder;
import org.kie.api.builder.KieFileSystem;
import org.kie.api.builder.KieRepository;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;
import org.kie.internal.io.ResourceFactory;
import org.kie.spring.KModuleBeanFactoryPostProcessor;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.io.Resource;
import java.io.IOException;
/**
 * 规则引擎配置类
 */
@Configuration
public class DroolsConfig {
    //指定规则文件存放的目录
    private static final String RULES_PATH = "rules/";
    private final KieServices kieServices = KieServices.Factory.get();
    @Bean
    @ConditionalOnMissingBean
    public KieFileSystem kieFileSystem() throws IOException {
        KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
        ResourcePatternResolver resourcePatternResolver = 
            new PathMatchingResourcePatternResolver();
        Resource[] files = 
            resourcePatternResolver.getResources("classpath*:" + RULES_PATH + "*.*");
        String path = null;
        for (Resource file : files) {
            path = RULES_PATH + file.getFilename();
            kieFileSystem.write(ResourceFactory.newClassPathResource(path, "UTF-8"));
        }
        return kieFileSystem;
    }
    @Bean
    @ConditionalOnMissingBean
    public KieContainer kieContainer() throws IOException {
        KieRepository kieRepository = kieServices.getRepository();
        kieRepository.addKieModule(kieRepository::getDefaultReleaseId);
        KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem());
        kieBuilder.buildAll();
        return kieServices.newKieContainer(kieRepository.getDefaultReleaseId());
    }
    @Bean
    @ConditionalOnMissingBean
    public KieBase kieBase() throws IOException {
        return kieContainer().getKieBase();
    }
    @Bean
    @ConditionalOnMissingBean
    public KModuleBeanFactoryPostProcessor kiePostProcessor() {
        return new KModuleBeanFactoryPostProcessor();
    }
}

第五步：创建RuleService类