从工作记忆中检索特定类型的事实 [英] Retrieving facts of a specific type from working memory
问题描述
我不需要检索所有事实,而是需要从工作记忆中检索特定类型的事实。
Instead of retrieving all facts i need to retrieve specific type of facts from working memory.
我了解到可以从工作记忆中检索所有事实,如下所示。
i learnt that i can retrieve all the facts from working memory as below.
drools.getWorkingMemory().getWorkingMemoryEntryPoint("Stream").getObjects();
请提供一些指针,以从工作内存中检索特定类型的对象。
Please provide some pointers to retrieve specific type of objects from working memory.
推荐答案
可以使用查询代替使用getObjects()方法。查询就像没有RHS的规则:
Instead of using the getObjects() method you could use a query. Queries are like rules without RHS:
query "getObjectsOfClassA"
$result: ClassA()
end
您可以在查询中使用DRL语言的所有功能来创建真正复杂的匹配模式。您甚至还可以将参数传递给查询: http://docs.jboss.org/drools/release/5.5.0.Final/drools-expert-docs/html_single/#d0e7632
You can use all the power of DRL language inside your queries to create really complex matching patterns. You can even pass arguments to queries too: http://docs.jboss.org/drools/release/5.5.0.Final/drools-expert-docs/html_single/#d0e7632
然后,在Java代码中,您可以使用以下代码调用查询:
Then, in your java code, you can invoke your query using:
QueryResults results = ksession.getQueryResults( "getObjectsOfClassA" );
for ( QueryResultsRow row : results ) {
ClassA classA = ( ClassA ) row.get( "$result" ); //you can retrieve all the bounded variables here
//do whatever you want with classA
}
如果需要所有ClassA的集合,则可以在查询中使用一个累加函数。
If you need the set of all ClassA you can use an accumulate function in your query.
希望它会有所帮助,
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