背景:

我正在开发一个应用程序，它根据一组 drools 规则将输入对象转换为两个输出对象之一。输出对象直到运行时才为人所知，它是在要执行的第一个规则中创建的。

这是创建输出对象的规则和示例转换规则:

rule "Initialization"
    dialect "java"
    salience 1000
    no-loop true
    when
        t : Trade()
    then 
        if(t.getTran().getInsType().equalsIgnoreCase("EEO") ||
           t.getTran().getInsType().equalsIgnoreCase("EEF"))
        {
            insert(new Option());
        }
        else
        {
            insert(new Swap());
        }
end

rule "Example Rule"
    dialect "java"
    when
        t : Trade()
        opt : Option()
    then
        opt.setCounterpartyName(t.getTran().getCParty());
end

这是调用规则的代码:

private void test(){
    for(File xmlFile : getXmlFilesFromDirectory(XML_DIRECTORY))
    {
        Trade trade = (Trade)unmarshall(xmlFile, Trade.class);

        KnowledgeBase kbase = readKnowledgeBase();

        StatelessKnowledgeSession ksession = kbase.newStatelessKnowledgeSession();
        KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory.newConsoleLogger(ksession);

        List<Command> commands = new ArrayList<Command>();
        commands.add(CommandFactory.newInsert(trade, "trade"));
        commands.add(CommandFactory.newFireAllRules());

        ExecutionResults results = ksession.execute(CommandFactory.newBatchExecution(commands));
        logger.close();
    }
 }

private static KnowledgeBase readKnowledgeBase() throws Exception 
{
    KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
    kbuilder.add(ResourceFactory.newClassPathResource("security-transformation.drl"), ResourceType.DRL);
    KnowledgeBuilderErrors errors = kbuilder.getErrors();
    if (errors.size() > 0) 
    {
        for (KnowledgeBuilderError error: errors) 
        {
            System.err.println(error);
        }

        throw new IllegalArgumentException("Could not parse knowledge.");
    }

    KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
    kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
    return kbase;
}

问题:

当我执行规则时，我没有在返回的事实中收到输出对象。我收到了交易对象，但我没有取回选项或交换对象，具体取决于第一条规则添加到工作内存中的对象。

问题:

如何在运行时在 drl 中将事实添加到工作内存并在无状态 session 的执行结果中检索它们？

编辑: 我需要使用 drools 查询吗？

最佳答案

我继续使用 drools 查询。我会为任何其他人发布代码。

查询添加到上述规则(对象扩展 BaseTrade):

query "GetOutputObj"
    baseTrade: BaseTrade()
end

从执行结果中获取查询结果的代码:

    StatelessKnowledgeSession ksession = this.kbase.newStatelessKnowledgeSession();

    KnowledgeRuntimeLogger klogger = configureKnowledgeRuntimeLogger(ksession);

    List<Command> commands = new ArrayList<Command>();
    commands.add(CommandFactory.newInsert(inputObj, "inputObj"));
    commands.add(CommandFactory.newFireAllRules());
    commands.add(CommandFactory.newQuery("outputObj", "GetOutputObj"));

    ExecutionResults results = ksession.execute(CommandFactory.newBatchExecution(commands));

    QueryResults queryResults = ((NativeQueryResults)results.getValue("baseTrade")).getResults();

    try
    {
        Iterator iter = queryResults.iterator();
        while(iter.hasNext())
        {
            QueryResult result = iter.next();

            //There can be only one... just like Highlander
            //Could switch this up and return a list, but we only expect one thing from here.
            return (BaseTrade) result.get("baseTrade");
        }
    }
    finally
    {
        if(klogger != null)
        {
            klogger.close();
        }
    }

关于java - 如何在运行时在 Drools DRL 中将事实添加到工作内存并在无状态 session 的执行结果中检索它们？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/5872215/