Drools动态更新规则

Drools动态规则加载

• Drools简介
• 动态加载规则
• • 1. 项目依赖
  • 2. 实现

Drools简介

简单说明一下规则动态插拔使用到的Drools相关类。

类名	使用说明
KnowledgeBuilder	在业务代码中收集已编写的规则,并对规则文件进行编译,生成编译好的KnowledgePackage 集合,提供给其他API使用。通过其提供的hasErrors()方法获得编译过程中是否有错,getErrors()方法打印错误信息。支持drl文件、dslr文件和xls文件等。
KnowledgePackage	存放编译好的规则对象
KnowledgeBase	收集应用当中知识（knowledge）定义的知识库对象（KnowledgePackage）在一个 KnowledgeBase当中可以包含普通的规则（rule）、规则流(rule flow)、函数定义(function)、用户自定义对象（type model）等，并创建session对象（StatefulKnowledgeSession和StatelessKnowledgeSession）

动态加载规则

1. 项目依赖

		<dependency>
			<groupId>org.drools</groupId>
			<artifactId>drools-compiler</artifactId>
			<version>7.37.0.Final</version>
		</dependency>
		<dependency>
			<groupId>org.drools</groupId>
			<artifactId>drools-core</artifactId>
			<version>7.37.0.Final</version>
		</dependency>
		<dependency>
			<groupId>org.drools</groupId>
			<artifactId>drools-templates</artifactId>
			<version>7.37.0.Final</version>
		</dependency>

2. 实现

(1) 新增规则

首先，新增规则，通过KnowledgeBuilder收集规则，将规则文件进行编译；然后通过KnowledgeBuilder.getKnowledgePackages()方法获取KnowledgePackage；最后将KnowledgePackage对象存入KnowledgeBase，完成对规则库的动态插入规则。

    /**
     * @Description: 对knowledgeBase操作，规则库新增规则操作
     * @Param: InternalKnowledgeBase knowledgeBase 规则库
     * @Param: String ruleContent 规则内容
     * @return:
     */
    private void addKnowledgePackages(InternalKnowledgeBase knowledgeBase, String ruleContent) {
        try {
            KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
            Resource resource = ResourceFactory.newReaderResource(new StringReader(ruleContent));
            kbuilder.add(resource, ResourceType.DRL);
            if (kbuilder.hasErrors()) {
                log.info("ADD RULE FILE ERROR: " + kbuilder.getErrors().toString());
            }
            knowledgeBase.addPackages(kbuilder.getKnowledgePackages());
        } catch (Exception e) {
            log.error(e.getMessage(), e);
        }
    }

(2) 删除规则

使用getRule()、removeRule()方法实现规则删除。

    /**
     * @Description: 删除规则
     * @Param: ruleName 规则名称
     * @Param: knowledgeBase 规则库
     * @Param: packageName 包命名
     * @return: 
     */
    private void delRule(String ruleName, InternalKnowledgeBase knowledgeBase, String packageName) {
        Rule rule = knowledgeBase.getRule(packageName, ruleName);
        if (rule != null) {
            knowledgeBase.removeRule(packageName, ruleName);
            log.info("Del RuleName : {}", ruleName);
        }
    }

(3) 更新规则

更新规则过程就是重复上述删除+新增的过程，不再赘述。

最后，贴一下规则示例，仅供参考：

package rule.noticepkg
import java.util.*;
import com.indocloud.indo.oss.fm.engine.dto.AlarmDTO;
import org.drools.core.impl.InternalKnowledgeBase;
import org.drools.core.impl.KnowledgeBaseFactory;
import org.kie.internal.builder.KnowledgeBuilder;
import org.kie.internal.builder.KnowledgeBuilderError;
import org.kie.internal.builder.KnowledgeBuilderErrors;
import org.kie.internal.builder.KnowledgeBuilderFactory;
import org.kie.internal.io.ResourceTypeImpl;
import org.kie.internal.io.ResourceFactory;
import org.kie.internal.logger.KnowledgeRuntimeLoggerFactory;
import org.kie.internal.runtime.StatefulKnowledgeSession;
import function com.indocloud.indo.oss.fm.engine.util.AlarmExecuteActionUtils.executeAction;

rule "c38f77a9a883424993c59c48b338dbf0"
  lock-on-active true
  salience 2
	when
		$alarm:AlarmDTO(originType == 'alarm' && originSeverity == '4')
	then
	   HashMap<String,Object> actionMap = new HashMap<String,Object>();
	   actionMap.put("frnType","2");
       executeAction(actionMap,$alarm,"7","c38f77a9a883424993c59c48b338dbf0");
end