How to integrate Drools rule engine in SpringBoot2

1. Introduction to Drools engine

1. Basic introduction

Drools is a java-based rule engine, open source, which can Complex and changeable rules are freed from hard coding and stored in files in the form of rule scripts, so that rule changes can take effect immediately in the online environment without modifying the code and restarting the machine. It has the characteristics of easy access to enterprise policies, easy adjustment and easy management. As an open source business rules engine, it complies with industry standards, is fast and efficient.

2. Rule syntax

(1), Demonstration drl file format

package droolRule ;
import org.slf4j.Logger
import org.slf4j.LoggerFactory ;
dialect "java"
rule "paramcheck1"
  when 
  then
    final Logger LOGGER = LoggerFactory.getLogger("param-check-one 规则引擎") ;
    LOGGER.info("参数");
end

(2), Grammar description

· File format

Can be .drl, xml files, or hard-coded Java code blocks;

· package

In the rule file, package is required Defined, it must be placed in the first line of the rule file;

·import

The external variable used by the rule file can be a class or a class. Accessible static method;

· rule

Define a rule. paramcheck1 rule name. Rules usually contain three parts: attributes, conditions, and results;

2. Integrate SpringBoot framework

1. Project structure

SpringBoot2 integrates Drools rule engine to achieve efficient business rules

2, core dependencies

<!--drools规则引擎-->
<dependency>
  <groupid>org.drools</groupid>
  <artifactid>drools-core</artifactid>
  <version>7.6.0.Final</version>
</dependency>
<dependency>
  <groupid>org.drools</groupid>
  <artifactid>drools-compiler</artifactid>
  <version>7.6.0.Final</version>
</dependency>
<dependency>
  <groupid>org.drools</groupid>
  <artifactid>drools-templates</artifactid>
  <version>7.6.0.Final</version>
</dependency>
<dependency>
  <groupid>org.kie</groupid>
  <artifactid>kie-api</artifactid>
  <version>7.6.0.Final</version>
</dependency>
<dependency>
  <groupid>org.kie</groupid>
  <artifactid>kie-spring</artifactid>
  <version>7.6.0.Final</version>
</dependency>

3, configuration file

@Configuration
public class RuleEngineConfig {
  private static final Logger LOGGER = LoggerFactory.getLogger(RuleEngineConfig.class) ;
  private static final String RULES_PATH = "droolRule/";
  private final KieServices kieServices = KieServices.Factory.get();
  @Bean
  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();
      LOGGER.info("path="+path);
      kieFileSystem.write(ResourceFactory.newClassPathResource(path, "UTF-8"));
    }
    return kieFileSystem;
  }
  @Bean
  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
  public KieBase kieBase() throws IOException {
    return kieContainer().getKieBase();
  }
  @Bean
  public KieSession kieSession() throws IOException {
    return kieContainer().newKieSession();
  }
  @Bean
  public KModuleBeanFactoryPostProcessor kiePostProcessor() {
    return new KModuleBeanFactoryPostProcessor();
  }
}

In this way, the environment integration is completed.

3. Demonstration case

1. Rule file

Rule 1

dialect "java"
rule "paramcheck1"
salience 99
when queryParam : QueryParam(paramId != null && paramSign.equals("+"))
  resultParam : RuleResult()
then
  final Logger LOGGER = LoggerFactory.getLogger("param-check-one 规则引擎") ;
  LOGGER.info("参数:getParamId="+queryParam.getParamId()+";getParamSign="+queryParam.getParamSign());
  RuleEngineServiceImpl ruleEngineService = new RuleEngineServiceImpl() ;
  ruleEngineService.executeAddRule(queryParam);
  resultParam.setPostCodeResult(true);
end

Rule 2

dialect "java"
rule "paramcheck2"
salience 88
when queryParam : QueryParam(paramId != null && paramSign.equals("-"))
  resultParam : RuleResult()
then
  final Logger LOGGER = LoggerFactory.getLogger("param-check-two 规则引擎") ;
  LOGGER.info("参数:getParamId="+queryParam.getParamId()+";getParamSign="+queryParam.getParamSign());
  RuleEngineServiceImpl ruleEngineService = new RuleEngineServiceImpl() ;
  ruleEngineService.executeRemoveRule(queryParam);
  resultParam.setPostCodeResult(true);
end

Rule description:

A. The larger the value of salience, the higher the priority;

B. Rule process: If paramId is not null, The parameter identifier is "number", which is used to add rules, and - number, which is used to remove rules.

2. Rule execution code

@Service
public class RuleEngineServiceImpl implements RuleEngineService {
  private static final Logger LOGGER = LoggerFactory.getLogger(RuleEngineServiceImpl.class) ;
  @Override
  public void executeAddRule(QueryParam param) {
    LOGGER.info("参数数据:"+param.getParamId()+";"+param.getParamSign());
    ParamInfo paramInfo = new ParamInfo() ;
    paramInfo.setId(param.getParamId());
    paramInfo.setParamSign(param.getParamSign());
    paramInfo.setCreateTime(new Date());
    paramInfo.setUpdateTime(new Date());
    ParamInfoService paramInfoService = (ParamInfoService)SpringContextUtil.getBean("paramInfoService") ;
    paramInfoService.insertParam(paramInfo);
  }
  @Override
  public void executeRemoveRule(QueryParam param) {
    LOGGER.info("参数数据:"+param.getParamId()+";"+param.getParamSign());
    ParamInfoService paramInfoService = (ParamInfoService)SpringContextUtil.getBean("paramInfoService") ;
    ParamInfo paramInfo = paramInfoService.selectById(param.getParamId());
    if (paramInfo != null){
      paramInfoService.removeById(param.getParamId()) ;
    }
  }
}

3. Rule calling interface

@RestController
@RequestMapping("/rule")
public class RuleController {
  @Resource
  private KieSession kieSession;
  @Resource
  private RuleEngineService ruleEngineService ;
  @RequestMapping("/param")
  public void param (){
    QueryParam queryParam1 = new QueryParam() ;
    queryParam1.setParamId("1");
    queryParam1.setParamSign("+");
    QueryParam queryParam2 = new QueryParam() ;
    queryParam2.setParamId("2");
    queryParam2.setParamSign("-");
    // 入参
    kieSession.insert(queryParam1) ;
    kieSession.insert(queryParam2) ;
    kieSession.insert(this.ruleEngineService) ;
    // 返参
    RuleResult resultParam = new RuleResult() ;
    kieSession.insert(resultParam) ;
    kieSession.fireAllRules() ;
  }
}

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