使用Java代码访问Drools返回的事实对象

user3854719 发表于 Dev

用户名

我有一个通过Guvnor控制台创建的流口水规则，如果满足条件，该规则将验证事实并将事实插入工作内存中。规则是：

    1. | rule "EligibilityCheck001" 
    2. |     dialect "mvel" 
    3. |     when 
    4. |         Eligibility( XXX== "XXX" , YYY== "YYY" , ZZZ== "ZZZ" , BBB == "BBB" ) 
    5. |     then 
    6. |         EligibilityInquiry fact0 = new EligibilityInquiry(); 
    7. |         fact0.setServiceName( "ABCD" ); 
    8. |         fact0.setMemberStatus( true ); 
    9. |         insert(fact0 ); 
   10. |         System.out.println( "Hello from Drools"); 
   11. | end

执行规则的Java代码如下

RuleAgent ruleAgent = RuleAgent.newRuleAgent("/Guvnor.properties");
RuleBase ruleBase = ruleAgent.getRuleBase();
FactType factType = ruleBase.getFactType("mortgages.Eligibility");

Object obj = factType.newInstance();
factType.set(obj, "XXX", "XXX");
factType.set(obj, "YYY", "YYY");
factType.set(obj, "ZZZ", "XXX");
factType.set(obj, "BBB", "BBB");

WorkingMemory workingMemory = ruleBase.newStatefulSession();
workingMemory.insert(obj);
workingMemory.fireAllRules();
System.out.println("After drools execution");
long count = workingMemory.getFactCount();
System.out.println("count " + count);

一切看起来都很不错，输出如下：

Hello from Drools
After drools execution
count 2

我似乎找不到找到将EligibilityInquiry事实对象恢复到我的Java代码中并获取上述（serviceName和status）规则中设置的属性的方法。我已经使用了这种StatefulSession方法。

属性文件具有通过用户名和密码进行基本身份验证的快照链接。总共有2个事实：EligibilityInquiry和Eligibility。

我对流口水是相当陌生的，对上述任何帮助都将受到赞赏。

异想天开

（注意：我固定了语句的顺序，即错字（“ XX”），并从输出中删除了注释。这不足为奇。）

此代码段假定EligibilityInquiry也在DRL中声明了该代码。

FactType eligInqFactType = ruleBase.getFactType("mortgages", "EligibilityInquiry");
Class<?> eligInqClass = eligInqFactType.getFactClass();
ObjectFilter filter = new FilterByClass( eligInqClass );
Collection<Object> eligInqs = workingMemory.getObjects( filter );

过滤器是

public class FilterByClass implements ObjectFilter {
    private Class<?> theClass;
    public FilterByClass( Class<?> clazz ){
        theClass = clazz;
    }
    public boolean accept(Object object){
        return theClass.isInstance( object );
    } 
}

您可能还会使用query，它需要大约相同数量的代码。

// DRL code
query "eligInqs" 
    eligInq : EligibilityInquiry()
end

// after return from fireAllRules
QueryResults results = workingMemory.getQueryResults( "eligInqs" );
for ( QueryResultsRow row : results ) {
    Object eligInqObj = row.get( "eligInq" );
    System.out.println( eligInqClass.cast( eligInqObj ) );
}

或者，您可以调用workingMemory.getObjects()并迭代该集合并检查每个对象的类。

for( Object obj: workingMemory.getObjects() ){
    if( obj.isInstance( eligInqClass ) ){
        System.out.println( eligInqClass.cast( eligInqObj ) );
    }
}

或者，您可以（有或没有插入创建的EligibilityInquiry对象作为事实）将事实添加到中global java.util.List eligInqList并在Java代码中进行迭代。请注意，的APIStatefulKnowledgeSession是必需的（而不是WorkingMemory）。

   // Java - prior to fireAllRules
   StatefulKnowledgeSession kSession() = ruleBase.newStatefulSession();

   List<?> list = new ArrayList();
   kSession.setGlobal( "eligInqList", list );

   // DRL
   global java.util.List eligInqList;

   // in a rule
   then
       EligibilityInquiry fact0 = new EligibilityInquiry(); 
       fact0.setServiceName( "ABCD" ); 
       fact0.setMemberStatus( true ); 
       insert(fact0 );  
       eligInqList.add( fact0 ); 
   end

   // after return from fireAllRules
   for( Object elem: list ){
    System.out.println( eligInqClass.cast( elem ) );
   }