java - 如何在 drools 7 中创建可重复使用的 KieBase

Question

我们通过以下方式实用地创建 KIEBase，并将编译后的 Kiebase 存储在 java 映射中:

private static Map<String, KieBase> kieBaseMap = new HashMap<>();

public setKieBaseMap(String groupId,String drl){
    KieHelper kieHelper = new KieHelper();
    kieHelper.addContent(drl, ResourceType.DRL);
    Results results = kieHelper.verify(); 
    kieBaseMap.put(groupId,kieHelper.build()); 
}

StatelessKieSession buildKieSession(String ruleGroupId) {
    return kieBaseMap.get(ruleGroupId).newStatelessKieSession();
}

但是如果我们尝试再次执行相同的 Kiebase，我们会遇到以下异常:

java.lang.NullPointerException
    at org.drools.core.phreak.PhreakJoinNode.doLeftInserts(PhreakJoinNode.java:95)
    at org.drools.core.phreak.PhreakJoinNode.doNode(PhreakJoinNode.java:71)
    at org.drools.core.phreak.RuleNetworkEvaluator.switchOnDoBetaNode(RuleNetworkEvaluator.java:552)
    at org.drools.core.phreak.RuleNetworkEvaluator.evalBetaNode(RuleNetworkEvaluator.java:538)
    at org.drools.core.phreak.RuleNetworkEvaluator.evalNode(RuleNetworkEvaluator.java:373)
    at org.drools.core.phreak.RuleNetworkEvaluator.innerEval(RuleNetworkEvaluator.java:333)
    at org.drools.core.phreak.RuleNetworkEvaluator.outerEval(RuleNetworkEvaluator.java:169)
    at org.drools.core.phreak.RuleNetworkEvaluator.evaluateNetwork(RuleNetworkEvaluator.java:127)
    at org.drools.core.phreak.RuleExecutor.reEvaluateNetwork(RuleExecutor.java:212)
    at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:87)
    at org.drools.core.concurrent.AbstractRuleEvaluator.internalEvaluateAndFire(AbstractRuleEvaluator.java:34)
    at org.drools.core.concurrent.SequentialRuleEvaluator.evaluateAndFire(SequentialRuleEvaluator.java:43)
    at org.drools.core.common.DefaultAgenda.fireLoop(DefaultAgenda.java:1067)
    at org.drools.core.common.DefaultAgenda.internalFireAllRules(DefaultAgenda.java:1014)
    at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1006)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.internalFireAllRules(StatefulKnowledgeSessionImpl.java:1308)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1299)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1283)
    at org.drools.core.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:281)

我已经设置了drools.getWorkingMemory().getKnowledgeBase().getConfiguration().setProperty(SequentialOption.PROPERTY_NAME,"true")

按顺序执行所有规则。请帮助我为什么会收到此异常

Answer 1

由于我想以顺序方式运行议程组，因此需要在模块创建时自行设置 SequentialAgendaOption.DYNAMIC:

 kieSessionBuilder.setKieBaseMap(
        ruleGroupId, kieHelper.build(SequentialAgendaOption.DYNAMIC, SequentialOption.YES));

那么这个问题就没有出现