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
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package com.vip.jie.rule.util;
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import org.drools.compiler.kie.builder.impl.InternalKieModule;
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import org.kie.api.KieServices;
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import org.kie.api.builder.KieBuilder;
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import org.kie.api.builder.KieFileSystem;
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import org.kie.api.builder.ReleaseId;
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import org.kie.api.builder.model.KieBaseModel;
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import org.kie.api.builder.model.KieModuleModel;
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import org.kie.api.builder.model.KieSessionModel;
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import org.kie.api.conf.EqualityBehaviorOption;
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import org.kie.api.conf.EventProcessingOption;
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import java.io.IOException;
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/**
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* 动态生成kjar
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* @author jie01.zhu
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* @DateTime 2018/3/19 22:14
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*/
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public class DroolsUtils {
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/**
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* 创建默认的kbase和stateful的kiesession
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*
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* @param ks
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* @param isdefault
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* @return
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*/
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private static KieFileSystem createKieFileSystemWithKProject(KieServices ks, boolean isdefault) {
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KieModuleModel kproj = ks.newKieModuleModel();
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KieBaseModel kieBaseModel1 = kproj.newKieBaseModel("KBase").setDefault(isdefault)
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.setEqualsBehavior(EqualityBehaviorOption.EQUALITY)
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.setEventProcessingMode(EventProcessingOption.STREAM);
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// Configure the KieSession.
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kieBaseModel1.newKieSessionModel("KSession").setDefault(isdefault)
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.setType(KieSessionModel.KieSessionType.STATEFUL);
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KieFileSystem kfs = ks.newKieFileSystem();
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kfs.writeKModuleXML(kproj.toXML());
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return kfs;
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}
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/**
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* 创建kjar的pom
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*
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* @param releaseId
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* @param dependencies
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* @return
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*/
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private static String getPom(ReleaseId releaseId, ReleaseId... dependencies) {
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String pom = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
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+ "<project xmlns=\"http://maven.apache.org/POM/4.0.0\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
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+ " xsi:schemaLocation=\"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd\">\n"
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+ " <modelVersion>4.0.0</modelVersion>\n" + "\n" + " <groupId>" + releaseId.getGroupId()
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+ "</groupId>\n" + " <artifactId>" + releaseId.getArtifactId() + "</artifactId>\n" + " <version>"
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+ releaseId.getVersion() + "</version>\n" + "\n";
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if (dependencies != null && dependencies.length > 0) {
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pom += "<dependencies>\n";
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for (ReleaseId dep : dependencies) {
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pom += "<dependency>\n";
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pom += " <groupId>" + dep.getGroupId() + "</groupId>\n";
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pom += " <artifactId>" + dep.getArtifactId() + "</artifactId>\n";
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pom += " <version>" + dep.getVersion() + "</version>\n";
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pom += "</dependency>\n";
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}
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pom += "</dependencies>\n";
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}
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pom += "</project>";
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return pom;
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}
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/**
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* 初始化一个kjar：把原有的drl包含进新建的kjar中
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*
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* @param ks
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* @param releaseId
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* @return
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* @throws IOException
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*/
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public static InternalKieModule initKieJar(KieServices ks, ReleaseId releaseId) throws IOException {
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KieFileSystem kfs = createKieFileSystemWithKProject(ks, true);
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kfs.writePomXML(getPom(releaseId));
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KieBuilder kieBuilder = ks.newKieBuilder(kfs);
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if (!kieBuilder.buildAll().getResults().getMessages().isEmpty()) {
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throw new IllegalStateException("Error creating KieBuilder.");
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}
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return (InternalKieModule) kieBuilder.getKieModule();
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}
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public static InternalKieModule createKieJar(KieServices ks, ReleaseId releaseId, DroolsResource droolsResource) {
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KieFileSystem kfs = createKieFileSystemWithKProject(ks, true);
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kfs.writePomXML(getPom(releaseId));
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kfs.write("src/main/resources/" + droolsResource.getTargetResourceName(), droolsResource.getResource());
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KieBuilder kieBuilder = ks.newKieBuilder(kfs);
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if (!kieBuilder.getResults().getMessages().isEmpty()) {
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throw new IllegalStateException(
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"Error creating KieBuilder. errorMsg:" + kieBuilder.getResults().getMessages());
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}
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return (InternalKieModule) kieBuilder.getKieModule();
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}
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}
重点调用参考:
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String fileName = "jie-" + group + "-rules";
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/**
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* 指定kjar包
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*/
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final ReleaseId releaseId = kieServices.newReleaseId("com.vip.jie", fileName, "1.0.0");
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log.info("DroolsGetKieSession fileName:{}", fileName);
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log.info("[DroolsGetKieSession] drlStr:{}", drlStr);
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// 创建初始化的kjar
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InternalKieModule kJar = DroolsUtils.createKieJar(kieServices, releaseId,
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new DroolsResource(ResourceFactory.newByteArrayResource(drlStr.getBytes()),
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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:
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package com.vip.jie.rule.service.impl;
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import com.vip.jie.rule.object.User;
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import com.vip.jie.rule.service.RuleManager;
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import lombok.extern.slf4j.Slf4j;
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import org.junit.Test;
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import static junit.framework.TestCase.fail;
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/**
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* 规则测试
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* @author jie01.zhu
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* @DateTime 2018/3/19 21:17
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*
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*/
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@Slf4j
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public class RuleManagerImplTest {
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private RuleManager ruleManager = new RuleManagerImpl();
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private String getRuleContent() {
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StringBuilder stringBuilder = new StringBuilder();
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stringBuilder.append("import com.vip.jie.rule.object.User;\n");
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stringBuilder.append("rule test1 when\n");
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stringBuilder.append("user : User(age==20)\n");
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stringBuilder.append("then\n");
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stringBuilder.append("user.setName(\"张三\");\n");
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stringBuilder.append("end\n");
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return stringBuilder.toString();
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}
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@Test
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public void executeRule1() throws Exception {
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User user = new User();
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user.setAge(20);
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//调用规则
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ruleManager.executeRule("test1", getRuleContent(), user);
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log.info("test result:{}", user.toString());
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if (!"张三".equals(user.getName())) {
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fail("error rule");
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}
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}
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@Test
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public void executeRule2() throws Exception {
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User user = new User();
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user.setAge(21);
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//调用规则
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ruleManager.executeRule("test1", getRuleContent(), user);
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log.info("test result:{}", user.toString());
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if ("张三".equals(user.getName())) {
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fail("error rule");
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}
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}
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}
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
vipshop_ebs/朱杰
2018-03-19
原文地址：https://blog.csdn.net/vipshop_fin_dev/article/details/79618067