规则引擎drools封装

红太狼 2022-05-29 07:20 387阅读 0赞

一.前言

######     网上规则引擎drools介绍很多,并且有很多细致的说明,作者也不敢托大说自己的好用,但作者经过2个项目使用过规则引擎后,自己对规则引擎的理解并进行封装,对规则内容及如何使用,有自己的一番实践,并提供源代码,供大家参考 ######

**二.设计思路及具体代码**

**   ** 首先我希望是轻量级的使用drools,不希望使用太过复杂的架构,以这种思路入手,就可以与任何项目轻易融入,这样就需要能够将drools规则的来源,从规则文件(drl)中可以从maven和自己的数据库中获取,脚本是动态的,配合drools6.5支持通过maven接入的规则的API,就可以做到从任何处获取规则内容

**一个工具类DroolsUtils**

package com.vip.jie.rule.util;
    
    import org.drools.compiler.kie.builder.impl.InternalKieModule;
    import org.kie.api.KieServices;
    import org.kie.api.builder.KieBuilder;
    import org.kie.api.builder.KieFileSystem;
    import org.kie.api.builder.ReleaseId;
    import org.kie.api.builder.model.KieBaseModel;
    import org.kie.api.builder.model.KieModuleModel;
    import org.kie.api.builder.model.KieSessionModel;
    import org.kie.api.conf.EqualityBehaviorOption;
    import org.kie.api.conf.EventProcessingOption;
    
    import java.io.IOException;
    
    
    
    /**
     * 动态生成kjar
     * @author jie01.zhu
     * @DateTime 2018/3/19 22:14
     */
    public class DroolsUtils {
    
    	/**
    	 * 创建默认的kbase和stateful的kiesession
    	 *
    	 * @param ks
    	 * @param isdefault
    	 * @return
    	 */
    	private static KieFileSystem createKieFileSystemWithKProject(KieServices ks, boolean isdefault) {
    		KieModuleModel kproj = ks.newKieModuleModel();
    		KieBaseModel kieBaseModel1 = kproj.newKieBaseModel("KBase").setDefault(isdefault)
    				.setEqualsBehavior(EqualityBehaviorOption.EQUALITY)
    				.setEventProcessingMode(EventProcessingOption.STREAM);
    		// Configure the KieSession.
    		kieBaseModel1.newKieSessionModel("KSession").setDefault(isdefault)
    				.setType(KieSessionModel.KieSessionType.STATEFUL);
    		KieFileSystem kfs = ks.newKieFileSystem();
    		kfs.writeKModuleXML(kproj.toXML());
    		return kfs;
    	}
    
    	/**
    	 * 创建kjar的pom
    	 *
    	 * @param releaseId
    	 * @param dependencies
    	 * @return
    	 */
    	private static String getPom(ReleaseId releaseId, ReleaseId... dependencies) {
    		String pom = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
    				+ "<project xmlns=\"http://maven.apache.org/POM/4.0.0\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
    				+ "         xsi:schemaLocation=\"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd\">\n"
    				+ "  <modelVersion>4.0.0</modelVersion>\n" + "\n" + "  <groupId>" + releaseId.getGroupId()
    				+ "</groupId>\n" + "  <artifactId>" + releaseId.getArtifactId() + "</artifactId>\n" + "  <version>"
    				+ releaseId.getVersion() + "</version>\n" + "\n";
    		if (dependencies != null && dependencies.length > 0) {
    			pom += "<dependencies>\n";
    			for (ReleaseId dep : dependencies) {
    				pom += "<dependency>\n";
    				pom += "  <groupId>" + dep.getGroupId() + "</groupId>\n";
    				pom += "  <artifactId>" + dep.getArtifactId() + "</artifactId>\n";
    				pom += "  <version>" + dep.getVersion() + "</version>\n";
    				pom += "</dependency>\n";
    			}
    			pom += "</dependencies>\n";
    		}
    		pom += "</project>";
    		return pom;
    	}
    
    	/**
    	 * 初始化一个kjar：把原有的drl包含进新建的kjar中
    	 *
    	 * @param ks
    	 * @param releaseId
    	 * @return
    	 * @throws IOException
    	 */
    	public static InternalKieModule initKieJar(KieServices ks, ReleaseId releaseId) throws IOException {
    		KieFileSystem kfs = createKieFileSystemWithKProject(ks, true);
    		kfs.writePomXML(getPom(releaseId));
    		KieBuilder kieBuilder = ks.newKieBuilder(kfs);
    		if (!kieBuilder.buildAll().getResults().getMessages().isEmpty()) {
    			throw new IllegalStateException("Error creating KieBuilder.");
    		}
    		return (InternalKieModule) kieBuilder.getKieModule();
    	}
    
    	public static InternalKieModule createKieJar(KieServices ks, ReleaseId releaseId, DroolsResource droolsResource) {
    		KieFileSystem kfs = createKieFileSystemWithKProject(ks, true);
    		kfs.writePomXML(getPom(releaseId));
    		kfs.write("src/main/resources/" + droolsResource.getTargetResourceName(), droolsResource.getResource());
    
    		KieBuilder kieBuilder = ks.newKieBuilder(kfs);
    		if (!kieBuilder.getResults().getMessages().isEmpty()) {
    			throw new IllegalStateException(
    					"Error creating KieBuilder. errorMsg:" + kieBuilder.getResults().getMessages());
    		}
    		return (InternalKieModule) kieBuilder.getKieModule();
    	}
    
    
    }

**重点调用参考:**

String fileName = "jie-" + group + "-rules";
    /**
     * 指定kjar包
     */
    final ReleaseId releaseId = kieServices.newReleaseId("com.vip.jie", fileName, "1.0.0");
    
    log.info("DroolsGetKieSession fileName:{}", fileName);
    log.info("[DroolsGetKieSession] drlStr:{}", drlStr);
    // 创建初始化的kjar
    InternalKieModule kJar = DroolsUtils.createKieJar(kieServices, releaseId,
     new DroolsResource(ResourceFactory.newByteArrayResource(drlStr.getBytes()),
     fileName + ".drl"));

其次再将如何让使用者可以很灵活的接入,利用可变参数类型,将入参对象无限制传入,由规则脚本去决定入参的变化,通过此种方式可以比较好的实现业务灵活接入

**如下单元测试类:**

package com.vip.jie.rule.service.impl;
    
    
    import com.vip.jie.rule.object.User;
    import com.vip.jie.rule.service.RuleManager;
    import lombok.extern.slf4j.Slf4j;
    import org.junit.Test;
    
    import static junit.framework.TestCase.fail;
    
    /**
     * 规则测试
     *  @author jie01.zhu
     *	@DateTime 2018/3/19 21:17
     *
     */
    @Slf4j
    public class RuleManagerImplTest {
    
    	private RuleManager ruleManager = new RuleManagerImpl();
    
    	private String getRuleContent() {
    		StringBuilder stringBuilder = new StringBuilder();
    
    		stringBuilder.append("import com.vip.jie.rule.object.User;\n");
    		stringBuilder.append("rule test1 when\n");
    		stringBuilder.append("user : User(age==20)\n");
    		stringBuilder.append("then\n");
    		stringBuilder.append("user.setName(\"张三\");\n");
    		stringBuilder.append("end\n");
    		return stringBuilder.toString();
    	}
    
    	@Test
    	public void executeRule1() throws Exception {
    
    		User user = new User();
    		user.setAge(20);
    
    		//调用规则
    		ruleManager.executeRule("test1", getRuleContent(), user);
    		log.info("test result:{}", user.toString());
    
    		if (!"张三".equals(user.getName())) {
    			fail("error rule");
    		}
    	}
    
    	@Test
    	public void executeRule2() throws Exception {
    
    		User user = new User();
    		user.setAge(21);
    
    		//调用规则
    		ruleManager.executeRule("test1", getRuleContent(), user);
    		log.info("test result:{}", user.toString());
    
    		if ("张三".equals(user.getName())) {
    			fail("error rule");
    		}
    	}
    }

**三.对应示例源代码获取方式**

**githup:**

https://github.com/jie01/drools-demo

**csdn资源下载地址:**

https://download.csdn.net/download/vipshop\_fin\_dev/10296393

还有一些关于安全性及与spring的封装思路,作者表示还会继续完善,并还不是最终版本,有需要可以持续关注-\_-!

## **与当前文章有关联的链接** ##

[业务框架之个性化监控方案][Link 1]

vipshop\_ebs/朱杰

2018-03-19

[Link 1]: http://blog.csdn.net/vipshop_fin_dev/article/details/79313432