SpringBoot整合easy-rules規則引擎的流程是什麼

一、概述​​

透過將業務規則配置的設定檔中，可以精簡程式碼，同時已於維護，當規則修改時，只需要修改設定檔即可。 easy-rules是一個小巧的規則引擎，支援spring的SPEL表達式，同時也支援 Apache JEXL 表達式和 MVL 表達式。

二、專案中加入依賴

在專案的gradle中增加依賴關係。

build.gradle:

plugins {
    id 'org.springframework.boot' version '3.0.5'
    id 'io.spring.dependency-management ' version '1.1.0'
    id 'java'
}

group = 'cn.springcamp'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17 '

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
    testCompile ies {
    mavenCentral()
}

dependencies {

    implementation "org.springframework.boot:spring-boot-starter-json"
    implementation 'org.spring-boot-starter-json"
    implementation 'org.springframework.boot:springsp -starter-validation'

    implementation 'org.jeasy:easy-rules-core:4.1.0'

    implementation 'org.jeasy:easy-rules-spel:4.1.0'
    implementation 'org. jeasy:easy-rules-support:4.1.0'
    annotationProcessor 'org.projectlombok:lombok'
    testAnnotationProcessor 'org.projectlombok:lombok'
  testAnnotationProcessor 'org.projectlombok:lombok'
   -test"
    testImplementation 'org.junit.vintage:junit-vintage-engine'
    testImplementation 'org.junit.vintage:junit-vintage-engine'
}

#dependencyManagement {
    imports {

        mavenBom "org.springframework.cloud:spring-cloud-dependencies:2022.0.1"

    }
}
##testtest {##> }

三、設定檔

範例程式將業務規則放到設定檔中，業務規則設定檔(demo-rule.yml)程式碼:

name: "age rule"

description: ""

priority: 1

condition: "#person.getAdult() == false"

actions:

  - "T( java.lang.System).out.println(\"Shop: Sorry, you are not allowed to buy alcohol\")"

  - "#person.setAdult(true)"
  - "#person.setAge (18)"
---
name: "alcohol rule"
description: ""
priority: 1
condition: "#person.getAdult() == true"
actions:
  - "T(java.lang.System).out.println(\"Shop: you are now allowed to buy alcohol\")"


#設定檔中的規則透過condition 進行配置，當滿足規則時，會呼叫actions 中配置的動作。

範例專案使用了spring的SPEL表達式進行規則配置，設定檔中配置了2個規則，第一個規則透過
person

這個spring bean中的getAdult()判斷是否滿足規則，滿足規則時呼叫三個方法。

在spring-boot本身的設定檔中application.yml 設定規則檔：

rule:  skip-on-first-failed-rule: true

skip-on-first-applied-rule: false

  skip-on-first-non-triggered-rule: true

  rules:

    - rule-id: "demo"

    location: "classpath:demo-rule.yml"


四、程式碼中對規則引擎進行設定

透過
RuleEngineConfig

這個spring的設定類別對規則引擎進行設定：

@Slf4j
@EnableConfigurationProperties(RuleEngineConfigProperties.class)
@Configuration
public class RuleEngineConfig implements BeanFactoryAware {
    @Autowired(required = false)
    private List<RuleListener> ruleListeners;
    @Autowired(required = false)
    private List<RulesEngineListener> rulesEngineListeners;
    private BeanFactory beanFactory;
    @Bean
    public RulesEngineParameters rulesEngineParameters(RuleEngineConfigProperties properties) {
        RulesEngineParameters parameters = new RulesEngineParameters();
        parameters.setSkipOnFirstAppliedRule(properties.isSkipOnFirstAppliedRule());
        parameters.setSkipOnFirstFailedRule(properties.isSkipOnFirstFailedRule());
        parameters.setSkipOnFirstNonTriggeredRule(properties.isSkipOnFirstNonTriggeredRule());
        return parameters;
    }
    @Bean
    public RulesEngine rulesEngine(RulesEngineParameters rulesEngineParameters) {
        DefaultRulesEngine rulesEngine = new DefaultRulesEngine(rulesEngineParameters);
        if (!CollectionUtils.isEmpty(ruleListeners)) {
            rulesEngine.registerRuleListeners(ruleListeners);
        }
        if (!CollectionUtils.isEmpty(rulesEngineListeners)) {
            rulesEngine.registerRulesEngineListeners(rulesEngineListeners);
        }
        return rulesEngine;
    }
    @Bean
    public BeanResolver beanResolver() {
        return new BeanFactoryResolver(beanFactory);
    }
    @Bean
    public RuleEngineTemplate ruleEngineTemplate(RuleEngineConfigProperties properties, RulesEngine rulesEngine) {
        RuleEngineTemplate ruleEngineTemplate = new RuleEngineTemplate();
        ruleEngineTemplate.setBeanResolver(beanResolver());
        ruleEngineTemplate.setProperties(properties);
        ruleEngineTemplate.setRulesEngine(rulesEngine);
        return ruleEngineTemplate;
    }
    @Bean
    public RuleListener defaultRuleListener() {
        return new RuleListener() {
            @Override
            public boolean beforeEvaluate(Rule rule, Facts facts) {
                return true;
            }
            @Override
            public void afterEvaluate(Rule rule, Facts facts, boolean b) {
                log.info("-----------------afterEvaluate-----------------");
                log.info(rule.getName() + rule.getDescription() + facts.toString());
            }
            @Override
            public void beforeExecute(Rule rule, Facts facts) {
                log.info("-----------------beforeExecute-----------------");
                log.info(rule.getName() + rule.getDescription() + facts.toString());
            }
            @Override
            public void onSuccess(Rule rule, Facts facts) {
                log.info("-----------------onSuccess-----------------");
                log.info(rule.getName() + rule.getDescription() + facts.toString());
            }
            @Override
            public void onFailure(Rule rule, Facts facts, Exception e) {
                log.info("-----------------onFailure-----------------");
                log.info(rule.getName() + "----------" + rule.getDescription() + facts.toString() + e.toString());
            }
        };
    }
    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }
}

設定檔中設定了

ruleEngineTemplate

這個spring bean，透過ruleEngineTemplate觸發規則引擎的執行。 五、執行規則引擎

ruleEngineTemplate配置好後，我們可以在業務程式碼中執行規則引擎，處理設定檔中設定的業務規則：

最為演示，我們將規則引擎的執行程式碼放到了Application 的run 方法中，程式啟動後立即執行規則引擎：

@SpringBootApplication
public class Application implements CommandLineRunner {
    @Autowired
    RuleEngineTemplate ruleEngineTemplate;
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
    @Override
    public void run(String... args) {
        Person person = new Person();
        Facts facts = new Facts();
        facts.put("person", person);
        ruleEngineTemplate.fire("demo", facts);
    }
}

程式執行後可以看到控制台裡列印了 Shop: Sorry, you are not allowed to buy alcohol，這個內容對應的是我們在規則文件中的actions中配置的

"T(java.lang.System).out.println(\"Shop : Sorry, you are not allowed to buy alcohol\")"

，說明規則成功執行了。

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