规则引擎drools封装

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"?>
"
				+ "<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
"
				+ "         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
"
				+ "  <modelVersion>4.0.0</modelVersion>
" + "
" + "  <groupId>" + releaseId.getGroupId()
				+ "</groupId>
" + "  <artifactId>" + releaseId.getArtifactId() + "</artifactId>
" + "  <version>"
				+ releaseId.getVersion() + "</version>
" + "
";
		if (dependencies != null && dependencies.length > 0) {
			pom += "<dependencies>
";
			for (ReleaseId dep : dependencies) {
				pom += "<dependency>
";
				pom += "  <groupId>" + dep.getGroupId() + "</groupId>
";
				pom += "  <artifactId>" + dep.getArtifactId() + "</artifactId>
";
				pom += "  <version>" + dep.getVersion() + "</version>
";
				pom += "</dependency>
";
			}
			pom += "</dependencies>
";
		}
		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;
");
		stringBuilder.append("rule test1 when
");
		stringBuilder.append("user : User(age==20)
");
		stringBuilder.append("then
");
		stringBuilder.append("user.setName("张三");
");
		stringBuilder.append("end
");
		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

vipshop_ebs/朱杰

2018-03-19

原文地址：https://blog.csdn.net/vipshop_fin_dev/article/details/79618067