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我需要根据来自后端的数据启用/禁用 drl 文件中的某些规则。即为迪拜启用规则 1,2,3，为新加坡启用 1,3 所以，我通过 drools.getRule().getName() 如下。

rule "Apply 50% discount to VIP customers"
    enabled (checkenabled(drools.getRule().getName()))
when
    $s : Sale( customer.type == CustomerType.VIP )  
then
$s.setDiscount(0.50);
    System.out.println("VIP discount applied1" + drools.getRule().getName());
end

我在这方面遇到了错误。

Exception in thread "main" [Error: null pointer: drools.rule.name]
[Near : {... checkenabled(drools.rule.name) ....}]
                          ^
[Line: 1, Column: 14]
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:427)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:140)
    at org.mvel2.ast.ASTNode.optimize(ASTNode.java:159)
    at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:115)
    at org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:38)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:948)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:373)
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:140)
    at org.mvel2.ast.ASTNode.optimize(ASTNode.java:159)
    at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:115)
    at org.mvel2.MVELRuntime.execute(MVELRuntime.java:86)
    at org.mvel2.compiler.CompiledExpression.getDirectValue(CompiledExpression.java:123)
    at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:119)
    at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:113)
    at org.mvel2.MVEL.executeExpression(MVEL.java:930)
    at org.drools.core.base.mvel.MVELEnabledExpression.getValue(MVELEnabledExpression.java:92)
    at org.drools.core.definitions.rule.impl.RuleImpl.isEffective(RuleImpl.java:384)
    at org.drools.core.phreak.RuleExecutor.cancelAndContinue(RuleExecutor.java:326)
    at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:142)
    at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:94)
    at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:964)
    at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1234)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1239)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1212)
    at com.emirates.App.testGoodCustomer(App.java:95)
    at com.emirates.App.main(App.java:74)
Caused by: java.lang.NullPointerException
    at org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:393)
    ... 25 more
4

2 回答 2

0

它看起来像是“声明性议程”功能的一个很好的例子。这是基于用于阻止规则的规则。这是一个简单的例子：

import org.kie.api.runtime.rule.Match;
rule "Apply 50% discount"
  @Eager                     // required for each rule to be blocked
  @Category("Singapore")
when
  $s : Sale( article matches ".*PX" ) // anything
then
  System.out.println("VIP: " + drools.getRule().getName());
end

rule "CheckBlock"
  @Direct @Eager // required for each rule that blocks
when
  Location( $country: country )
  // $m: Match( Category == "Singapore" )
  $m: Match( rule.name == "Apply 50% discount" )
then
  kcontext.blockMatch( $m );
end

位置是一个简单的bean。如图所示，阻止规则可以访问“匹配”对象，该对象（神奇地）允许您匹配元数据或规则名称。当然，评估可能会访问 Location 中的某些方法，以对规则名称进行更复杂的检查。

请注意，您需要设置一个选项：

 KieBaseConfiguration config = ks.newKieBaseConfiguration();
 config.setOption( DeclarativeAgendaOption.ENABLED );

或使用 kmodule XML（请参阅文档）。

于 2015-01-27T10:45:18.530 回答
0

你为什么不使用AgendaFilter？

很容易使用，可以像这样在Java部分完成：

AgendaFilter myFilter = new RuleNameStartsWithAgendaFilter("DUBAI");
mySession.fireAllRules(filter);

myFilter = new RuleNameStartsWithAgendaFilter("SINGAPORE");
mySession.fireAllRules(filter);

AgendaFilter有多种变体：

  • 以。。开始
  • 以。。结束
  • 包含
  • 火柴

我不完全是你需要的，但它可能是一个提示；-)

于 2015-01-27T08:05:28.783 回答