最近，因工作需要做了规则引擎的调研，对比了多个规则引擎后，最终选择开源规则引擎Drools。
Drools的优点很多，而我决定使用Drools的原因主要是：
当然，Drools也有很多缺点：
为了能完全掌控Drools，最近一直在学习，使用各种方法学习Drools，通过在线文章、官方文档、官方API、视频教程等学习，并且有潜伏进一个Drools学习交流群，发现群里同学问的最多的一个问题就是：怎么样通过数据库动态加载规则？正好，我们也打算采用从数据库动态加载规则，并且我正好解决了这个问题，现在写篇文章分享出来给大家，希望能帮助到大家。
首先，通过代码生成规则模拟从数据库查询规则，每条规则记录包含：id（规则id，全局唯一）、sceneId（场景id，一个场景对应多个规则）、content（规则内容，既drl文件内容）。
然后，按场景动态加载规则，每个场景对应一个实际的业务场景，通过场景隔离不同的业务。
最后，执行应用指定场景规则，模拟不同业务场景下的规则应用。
<properties> <drools.version>7.20.0.Final</drools.version> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.kie</groupId> <artifactId>kie-api</artifactId> <version>${drools.version}</version> </dependency> <dependency> <groupId>org.drools</groupId> <artifactId>drools-core</artifactId> <version>${drools.version}</version> </dependency> <dependency> <groupId>org.drools</groupId> <artifactId>drools-compiler</artifactId> <version>${drools.version}</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies>package com.loujinhe.droolsdynamicloading.model;import lombok.Data;import lombok.ToString;/** * 规则信息 * * @author loujinhe * @date 2019/4/14 00:13 */@Data@ToStringpublic class RuleInfo { /** * 规则id，全局唯一 */ private Long id; /** * 场景id，一个场景对应多个规则，一个场景对应一个业务场景，一个场景对应一个kmodule */ private Long sceneId; /** * 规则内容，既drl文件内容 */ private String content;}这里通过代码生成规则记录模拟从数据库查询规则记录。
package com.loujinhe.droolsdynamicloading.service;import com.loujinhe.droolsdynamicloading.model.RuleInfo;import org.springframework.stereotype.Service;import java.text.MessageFormat;import java.text.SimpleDateFormat;import java.util.*;/** * 规则信息业务 * * @author loujinhe * @date 2019/4/14 00:20 */@Servicepublic class RuleInfoService { /** * 获取给定场景下的规则信息列表 * * @param sceneId 场景ID * @return 规则列表 */ public List<RuleInfo> getRuleInfoListBySceneId(Long sceneId) { Map<Long, List<RuleInfo>> sceneId2RuleInfoListMap = getRuleInfoListMap(); return sceneId2RuleInfoListMap.get(sceneId); } /** * 获取场景与规则信息列表的Map * * @return 场景规则信息列表Map，Map(sceneId : List < RuleInfo >) */ public Map<Long, List<RuleInfo>> getRuleInfoListMap() { Map<Long, List<RuleInfo>> sceneId2RuleInfoListMap = new HashMap<>(); List<RuleInfo> allRuleInfos = generateRuleInfoList(); for (RuleInfo ruleInfo : allRuleInfos) { List<RuleInfo> ruleInfos = sceneId2RuleInfoListMap.computeIfAbsent(ruleInfo.getSceneId(), k -> new ArrayList<>()); ruleInfos.add(ruleInfo); } return sceneId2RuleInfoListMap; } /** * 生成规则信息列表，注意场景id和规则id的对应关系 * * @return 规则信息列表 */ private List<RuleInfo> generateRuleInfoList() { int sceneNum = 5; int ruleNumPerScene = 3; int sceneFactor = 10000; List<RuleInfo> ruleInfos = new ArrayList<>(sceneNum * ruleNumPerScene); for (int i = 0; i < sceneNum; i++) { long sceneId = sceneFactor * (i + 1); for (int j = 0; j < ruleNumPerScene; j++) { long id = sceneId + (j + 1); ruleInfos.add(generateRuleInfo(sceneId, id)); } } return ruleInfos; } /** * 生成规则信息 * * @param sceneId 场景ID * @param id 规则ID * @return 规则信息 */ private RuleInfo generateRuleInfo(long sceneId, long id) { RuleInfo ruleInfo = new RuleInfo(); ruleInfo.setId(id); ruleInfo.setSceneId(sceneId); ruleInfo.setContent(generateRuleContent(sceneId, id)); return ruleInfo; } /** * 生成规则内容，每个场景id对应一个package，每个规则对应一个唯一的规则名 * * 每次生成规则时记录时间戳，用来验证动态加载效果 * * @param sceneId 场景ID * @param id 规则ID * @return 规则内容 */ private String generateRuleContent(long sceneId, long id) { String sceneIdStr = String.valueOf(sceneId); String idStr = String.valueOf(id); String nowStr = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date()); String content = "package rules.scene_{0};\n" + "\n" + "rule \"rule_{1}\"\n" + " when\n" + " eval(true);\n" + " then\n" + " System.out.println(\"{2} [{3}, {4}]\");\n" + "end\n"; return MessageFormat.format(content, sceneIdStr, idStr, nowStr, sceneIdStr, idStr); }}可以加载全部场景下的规则，也可以加载指定场景下的规则。
package com.loujinhe.droolsdynamicloading.drools;import com.loujinhe.droolsdynamicloading.model.RuleInfo;import com.loujinhe.droolsdynamicloading.service.RuleInfoService;import org.kie.api.KieServices;import org.kie.api.builder.KieBuilder;import org.kie.api.builder.KieFileSystem;import org.kie.api.builder.Message;import org.kie.api.builder.Results;import org.kie.api.builder.model.KieBaseModel;import org.kie.api.builder.model.KieModuleModel;import org.kie.api.runtime.KieContainer;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.ApplicationArguments;import org.springframework.boot.ApplicationRunner;import org.springframework.stereotype.Component;import java.text.MessageFormat;import java.util.List;import java.util.Map;import java.util.concurrent.ConcurrentHashMap;import java.util.concurrent.ConcurrentMap;/** * 规则加载器 * * @author loujinhe * @date 2019/4/14 00:06 */@Componentpublic class RuleLoader implements ApplicationRunner { /** * key:kcontainerName,value:KieContainer，每个场景对应一个KieContainer */ private final ConcurrentMap<String, KieContainer> kieContainerMap = new ConcurrentHashMap<>(); @Autowired private RuleInfoService ruleInfoService; @Override public void run(ApplicationArguments args) throws Exception { reloadAll(); } /** * 构造kcontainerName * * @param sceneId 场景ID * @return kcontainerName */ private String buildKcontainerName(long sceneId) { return "kcontainer_" + sceneId; } /** * 构造kbaseName * * @param sceneId 场景ID * @return kbaseName */ private String buildKbaseName(long sceneId) { return "kbase_" + sceneId; } /** * 构造ksessionName * * @param sceneId 场景ID * @return ksessionName */ private String buildKsessionName(long sceneId) { return "ksession_" + sceneId; } KieContainer getKieContainerBySceneId(long sceneId) { return kieContainerMap.get(buildKcontainerName(sceneId)); } /** * 重新加载所有规则 */ public void reloadAll() { Map<Long, List<RuleInfo>> sceneId2RuleInfoListMap = ruleInfoService.getRuleInfoListMap(); for (Map.Entry<Long, List<RuleInfo>> entry : sceneId2RuleInfoListMap.entrySet()) { long sceneId = entry.getKey(); reload(sceneId, entry.getValue()); } System.out.println("reload all success"); } /** * 重新加载给定场景下的规则 * * @param sceneId 场景ID */ public void reload(Long sceneId) { List<RuleInfo> ruleInfos = ruleInfoService.getRuleInfoListBySceneId(sceneId); reload(sceneId, ruleInfos); System.out.println("reload success"); } /** * 重新加载给定场景给定规则列表，对应一个kmodule * * @param sceneId 场景ID * @param ruleInfos 规则列表 */ private void reload(long sceneId, List<RuleInfo> ruleInfos) { KieServices kieServices = KieServices.get(); KieModuleModel kieModuleModel = kieServices.newKieModuleModel(); KieBaseModel kieBaseModel = kieModuleModel.newKieBaseModel(buildKbaseName(sceneId)); kieBaseModel.setDefault(true); kieBaseModel.addPackage(MessageFormat.format("rules.scene_{0}", String.valueOf(sceneId))); kieBaseModel.newKieSessionModel(buildKsessionName(sceneId)); KieFileSystem kieFileSystem = kieServices.newKieFileSystem(); for (RuleInfo ruleInfo : ruleInfos) { String fullPath = MessageFormat.format("src/main/resources/rules/scene_{0}/rule_{1}.drl", String.valueOf(sceneId), String.valueOf(ruleInfo.getId())); kieFileSystem.write(fullPath, ruleInfo.getContent()); } kieFileSystem.writeKModuleXML(kieModuleModel.toXML()); KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem).buildAll(); Results results = kieBuilder.getResults(); if (results.hasMessages(Message.Level.ERROR)) { System.out.println(results.getMessages()); throw new IllegalStateException("rule error"); } KieContainer kieContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId()); kieContainerMap.put(buildKcontainerName(sceneId), kieContainer); }}通过该辅助类可以获取指定场景下的KieSession，通过该KieSession可以与指定场景规则交互。
package com.loujinhe.droolsdynamicloading.drools;import org.kie.api.runtime.KieSession;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Component;/** * KieSession助手类 * * @author loujinhe * @date 2019/4/15 22:29 */@Componentpublic class KieSessionHelper { @Autowired private RuleLoader ruleLoader; /** * 获取KieSession * * @param sceneId 场景ID * @return KieSession */ public KieSession getKieSessionBySceneId(long sceneId) { return ruleLoader.getKieContainerBySceneId(sceneId).getKieBase().newKieSession(); }}包含动态加载指定场景规则功能，以及触发指定场景下的规则功能。
package com.loujinhe.droolsdynamicloading.controller;import com.loujinhe.droolsdynamicloading.drools.KieSessionHelper;import com.loujinhe.droolsdynamicloading.drools.RuleLoader;import org.kie.api.runtime.KieSession;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;/** * 规则测试 * * @author loujinhe * @date 2019/4/14 01:35 */@RequestMapping("rule")@RestControllerpublic class RuleController { @Autowired private RuleLoader ruleLoader; @Autowired private KieSessionHelper kieSessionHelper; @GetMapping("/") public String index() { System.out.println("index"); return "success"; } /** * 重新加载所有规则 */ @GetMapping("reload") public String reload() { System.out.println("reload all"); ruleLoader.reloadAll(); return "success"; } /** * 重新加载给定场景下的规则 * * @param sceneId 场景ID */ @GetMapping("reload/{sceneId}") public String reload(@PathVariable("sceneId") Long sceneId) { System.out.println("reload scene:" + sceneId); ruleLoader.reload(sceneId); return "success"; } /** * 触发给定场景规则 * * @param sceneId 场景ID */ @GetMapping("fire/{sceneId}") public String fire(@PathVariable("sceneId") Long sceneId) { System.out.println("fire scene:" + sceneId); KieSession kieSession = kieSessionHelper.getKieSessionBySceneId(sceneId); kieSession.fireAllRules(); kieSession.dispose(); return "success"; }}默认加载所有场景下的规则，启动时日志如下：
/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/bin/java -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=54524 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Djava.rmi.server.hostname=127.0.0.1 -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true "-javaagent:/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=54525:/Applications/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_181.jdk/Contents/Home/lib/tools.jar:/Users/loujinhe/project/IdeaProjects/drools-dynamic-loading/target/classes:/Users/loujinhe/.m2/repository/org/kie/kie-api/7.20.0.Final/kie-api-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/kie/soup/kie-soup-maven-support/7.20.0.Final/kie-soup-maven-support-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/slf4j/slf4j-api/1.7.26/slf4j-api-1.7.26.jar:/Users/loujinhe/.m2/repository/org/drools/drools-core/7.20.0.Final/drools-core-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/mvel/mvel2/2.4.4.Final/mvel2-2.4.4.Final.jar:/Users/loujinhe/.m2/repository/org/kie/kie-internal/7.20.0.Final/kie-internal-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/kie/soup/kie-soup-commons/7.20.0.Final/kie-soup-commons-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/kie/soup/kie-soup-project-datamodel-commons/7.20.0.Final/kie-soup-project-datamodel-commons-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/kie/soup/kie-soup-project-datamodel-api/7.20.0.Final/kie-soup-project-datamodel-api-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/commons-codec/commons-codec/1.11/commons-codec-1.11.jar:/Users/loujinhe/.m2/repository/org/drools/drools-compiler/7.20.0.Final/drools-compiler-7.20.0.Final.jar:/Users/loujinhe/.m2/repository/org/antlr/antlr-runtime/3.5.2/antlr-runtime-3.5.2.jar:/Users/loujinhe/.m2/repository/org/eclipse/jdt/core/compiler/ecj/4.6.1/ecj-4.6.1.jar:/Users/loujinhe/.m2/repository/com/thoughtworks/xstream/xstream/1.4.10/xstream-1.4.10.jar:/Users/loujinhe/.m2/repository/xmlpull/xmlpull/1.1.3.1/xmlpull-1.1.3.1.jar:/Users/loujinhe/.m2/repository/xpp3/xpp3_min/1.1.4c/xpp3_min-1.1.4c.jar:/Users/loujinhe/.m2/repository/com/google/protobuf/protobuf-java/3.6.1/protobuf-java-3.6.1.jar:/Users/loujinhe/.m2/repository/org/projectlombok/lombok/1.18.6/lombok-1.18.6.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot-starter-web/2.1.4.RELEASE/spring-boot-starter-web-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot-starter/2.1.4.RELEASE/spring-boot-starter-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot/2.1.4.RELEASE/spring-boot-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/2.1.4.RELEASE/spring-boot-autoconfigure-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot-starter-logging/2.1.4.RELEASE/spring-boot-starter-logging-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar:/Users/loujinhe/.m2/repository/ch/qos/logback/logback-core/1.2.3/logback-core-1.2.3.jar:/Users/loujinhe/.m2/repository/org/apache/logging/log4j/log4j-to-slf4j/2.11.2/log4j-to-slf4j-2.11.2.jar:/Users/loujinhe/.m2/repository/org/apache/logging/log4j/log4j-api/2.11.2/log4j-api-2.11.2.jar:/Users/loujinhe/.m2/repository/org/slf4j/jul-to-slf4j/1.7.26/jul-to-slf4j-1.7.26.jar:/Users/loujinhe/.m2/repository/javax/annotation/javax.annotation-api/1.3.2/javax.annotation-api-1.3.2.jar:/Users/loujinhe/.m2/repository/org/yaml/snakeyaml/1.23/snakeyaml-1.23.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot-starter-json/2.1.4.RELEASE/spring-boot-starter-json-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.9.8/jackson-databind-2.9.8.jar:/Users/loujinhe/.m2/repository/com/fasterxml/jackson/core/jackson-annotations/2.9.0/jackson-annotations-2.9.0.jar:/Users/loujinhe/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.9.8/jackson-core-2.9.8.jar:/Users/loujinhe/.m2/repository/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.9.8/jackson-datatype-jdk8-2.9.8.jar:/Users/loujinhe/.m2/repository/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.9.8/jackson-datatype-jsr310-2.9.8.jar:/Users/loujinhe/.m2/repository/com/fasterxml/jackson/module/jackson-module-parameter-names/2.9.8/jackson-module-parameter-names-2.9.8.jar:/Users/loujinhe/.m2/repository/org/springframework/boot/spring-boot-starter-tomcat/2.1.4.RELEASE/spring-boot-starter-tomcat-2.1.4.RELEASE.jar:/Users/loujinhe/.m2/repository/org/apache/tomcat/embed/tomcat-embed-core/9.0.17/tomcat-embed-core-9.0.17.jar:/Users/loujinhe/.m2/repository/org/apache/tomcat/embed/tomcat-embed-el/9.0.17/tomcat-embed-el-9.0.17.jar:/Users/loujinhe/.m2/repository/org/apache/tomcat/embed/tomcat-embed-websocket/9.0.17/tomcat-embed-websocket-9.0.17.jar:/Users/loujinhe/.m2/repository/org/hibernate/validator/hibernate-validator/6.0.16.Final/hibernate-validator-6.0.16.Final.jar:/Users/loujinhe/.m2/repository/javax/validation/validation-api/2.0.1.Final/validation-api-2.0.1.Final.jar:/Users/loujinhe/.m2/repository/org/jboss/logging/jboss-logging/3.3.2.Final/jboss-logging-3.3.2.Final.jar:/Users/loujinhe/.m2/repository/com/fasterxml/classmate/1.4.0/classmate-1.4.0.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-web/5.1.6.RELEASE/spring-web-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-beans/5.1.6.RELEASE/spring-beans-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-webmvc/5.1.6.RELEASE/spring-webmvc-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-aop/5.1.6.RELEASE/spring-aop-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-context/5.1.6.RELEASE/spring-context-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-expression/5.1.6.RELEASE/spring-expression-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-core/5.1.6.RELEASE/spring-core-5.1.6.RELEASE.jar:/Users/loujinhe/.m2/repository/org/springframework/spring-jcl/5.1.6.RELEASE/spring-jcl-5.1.6.RELEASE.jar com.loujinhe.droolsdynamicloading.DroolsDynamicLoadingApplication . ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v2.1.4.RELEASE)2019-05-11 01:26:16.189 INFO 5866 --- [ main] c.l.d.DroolsDynamicLoadingApplication : Starting DroolsDynamicLoadingApplication on loujinhedeMacBook-Pro.local with PID 5866 (/Users/loujinhe/project/IdeaProjects/drools-dynamic-loading/target/classes started by loujinhe in /Users/loujinhe/project/IdeaProjects/drools-dynamic-loading)2019-05-11 01:26:16.191 INFO 5866 --- [ main] c.l.d.DroolsDynamicLoadingApplication : No active profile set, falling back to default profiles: default2019-05-11 01:26:16.836 INFO 5866 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)2019-05-11 01:26:16.851 INFO 5866 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2019-05-11 01:26:16.851 INFO 5866 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.17]2019-05-11 01:26:16.910 INFO 5866 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2019-05-11 01:26:16.910 INFO 5866 --- [ main] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 696 ms2019-05-11 01:26:17.052 INFO 5866 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'2019-05-11 01:26:17.203 INFO 5866 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''2019-05-11 01:26:17.206 INFO 5866 --- [ main] c.l.d.DroolsDynamicLoadingApplication : Started DroolsDynamicLoadingApplication in 1.224 seconds (JVM running for 1.626)2019-05-11 01:26:17.220 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Loading kie.conf from jar:file:/Users/loujinhe/.m2/repository/org/drools/drools-core/7.20.0.Final/drools-core-7.20.0.Final.jar!/META-INF/kie.conf in classloader sun.misc.Launcher$AppClassLoader@18b4aac22019-05-11 01:26:17.221 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.drools.core.io.impl.ResourceFactoryServiceImpl2019-05-11 01:26:17.222 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.drools.core.marshalling.impl.MarshallerProviderImpl2019-05-11 01:26:17.222 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.drools.core.concurrent.ExecutorProviderImpl2019-05-11 01:26:17.222 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Loading kie.conf from jar:file:/Users/loujinhe/.m2/repository/org/kie/kie-internal/7.20.0.Final/kie-internal-7.20.0.Final.jar!/META-INF/kie.conf in classloader sun.misc.Launcher$AppClassLoader@18b4aac22019-05-11 01:26:17.223 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.kie.internal.services.KieAssemblersImpl2019-05-11 01:26:17.223 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.kie.internal.services.KieRuntimesImpl2019-05-11 01:26:17.224 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.kie.internal.services.KieWeaversImpl2019-05-11 01:26:17.224 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.kie.internal.services.KieBeliefsImpl2019-05-11 01:26:17.224 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Loading kie.conf from jar:file:/Users/loujinhe/.m2/repository/org/drools/drools-compiler/7.20.0.Final/drools-compiler-7.20.0.Final.jar!/META-INF/kie.conf in classloader sun.misc.Launcher$AppClassLoader@18b4aac22019-05-11 01:26:17.225 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.drools.compiler.kie.builder.impl.KieServicesImpl2019-05-11 01:26:17.226 INFO 5866 --- [ main] o.k.a.i.utils.ServiceDiscoveryImpl : Adding Service org.drools.compiler.builder.impl.KnowledgeBuilderFactoryServiceImpl2019-05-11 01:26:17.778 INFO 5866 --- [ main] o.d.c.k.builder.impl.KieRepositoryImpl : KieModule was added: MemoryKieModule[releaseId=org.default:artifact:1.0.0]2019-05-11 01:26:17.800 INFO 5866 --- [ main] o.d.c.k.builder.impl.KieRepositoryImpl : KieModule was added: MemoryKieModule[releaseId=org.default:artifact:1.0.0]2019-05-11 01:26:17.816 INFO 5866 --- [ main] o.d.c.k.builder.impl.KieRepositoryImpl : KieModule was added: MemoryKieModule[releaseId=org.default:artifact:1.0.0]2019-05-11 01:26:17.831 INFO 5866 --- [ main] o.d.c.k.builder.impl.KieRepositoryImpl : KieModule was added: MemoryKieModule[releaseId=org.default:artifact:1.0.0]2019-05-11 01:26:17.846 INFO 5866 --- [ main] o.d.c.k.builder.impl.KieRepositoryImpl : KieModule was added: MemoryKieModule[releaseId=org.default:artifact:1.0.0]reload all success8.1 首先，分别触发场景10000、20000、30000下的规则，访问url及日志如下：
http://localhost:8080/rule/fire/10000
http://localhost:8080/rule/fire/20000
http://localhost:8080/rule/fire/30000
2019-05-11 01:32:01.844 INFO 5866 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'2019-05-11 01:32:01.844 INFO 5866 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'2019-05-11 01:32:01.851 INFO 5866 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 7 msfire scene:1000020190511012617 [10000, 10002]20190511012617 [10000, 10003]20190511012617 [10000, 10001]fire scene:2000020190511012617 [20000, 20001]20190511012617 [20000, 20003]20190511012617 [20000, 20002]fire scene:3000020190511012617 [30000, 30001]20190511012617 [30000, 30002]20190511012617 [30000, 30003]通过分析日志发现，规则是按场景隔离的，并且规则的生成时间戳都是：20190511012617。
8.2 然后，加载场景20000下的规则，访问url及日志如下：
http://localhost:8080/rule/reload/20000
reload scene:200002019-05-11 01:34:45.988 INFO 5866 --- [nio-8080-exec-9] o.d.c.k.builder.impl.KieRepositoryImpl : KieModule was added: MemoryKieModule[releaseId=org.default:artifact:1.0.0]reload success通过分析日志发现，规则加载成功（应该）。
8.3 最后，分别触发场景10000、20000、30000下的规则，访问url及日志如下：
http://localhost:8080/rule/fire/10000
http://localhost:8080/rule/fire/20000
http://localhost:8080/rule/fire/30000
fire scene:1000020190511012617 [10000, 10002]20190511012617 [10000, 10003]20190511012617 [10000, 10001]fire scene:2000020190511013445 [20000, 20001]20190511013445 [20000, 20002]20190511013445 [20000, 20003]fire scene:3000020190511012617 [30000, 30001]20190511012617 [30000, 30002]20190511012617 [30000, 30003]通过分析日志发现，场景10000、30000的时间戳是一样的，跟第一次加载时的时间戳是一样的，而场景20000的时间戳不一样，为20190511013445正好是我们刚才手动动态加载时的时间戳，说明动态加载指定场景规则成功。
整个动态加载规则的核心代码就几行，核心代码如下：
/** * 重新加载给定场景给定规则列表，对应一个kmodule * * @param sceneId 场景ID * @param ruleInfos 规则列表 */ private void reload(long sceneId, List<RuleInfo> ruleInfos) { KieServices kieServices = KieServices.get(); KieModuleModel kieModuleModel = kieServices.newKieModuleModel(); KieBaseModel kieBaseModel = kieModuleModel.newKieBaseModel(buildKbaseName(sceneId)); kieBaseModel.setDefault(true); kieBaseModel.addPackage(MessageFormat.format("rules.scene_{0}", String.valueOf(sceneId))); kieBaseModel.newKieSessionModel(buildKsessionName(sceneId)); KieFileSystem kieFileSystem = kieServices.newKieFileSystem(); for (RuleInfo ruleInfo : ruleInfos) { String fullPath = MessageFormat.format("src/main/resources/rules/scene_{0}/rule_{1}.drl", String.valueOf(sceneId), String.valueOf(ruleInfo.getId())); kieFileSystem.write(fullPath, ruleInfo.getContent()); } kieFileSystem.writeKModuleXML(kieModuleModel.toXML()); KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem).buildAll(); Results results = kieBuilder.getResults(); if (results.hasMessages(Message.Level.ERROR)) { System.out.println(results.getMessages()); throw new IllegalStateException("rule error"); } KieContainer kieContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId()); kieContainerMap.put(buildKcontainerName(sceneId), kieContainer); }通过分析代码发现，动态加载规则的方式跟通过kmodule.xml配置文件加载规则的方式是对应的，如：KieModuleModel 对应kmodule节点，KieBaseModel对应kbase节点，并且最终也是通过转换成kmodule.xml配置文件的方式加载规则的，如：kieFileSystem.writeKModuleXML(kieModuleModel.toXML())。
Drools很好很强大，文档很烂很差劲，希望我的绵薄之力可以节省大家的宝贵时间。
备注
代码已提交到码云：https://gitee.com/loujinhe/drools-dynamic-loading
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