Question

我想在运行时动态地向现有KieSession添加新规则文件（或修改现有的规则文件）。

我找到了answer，并尝试了那里提到的解决方案，但得到了运行时异常。

使用的代码如下：

Driver.java ：

package app1;

import java.io.FileInputStream;
import java.io.FileNotFoundException;

import org.kie.api.KieBase;
import org.kie.api.KieServices;
import org.kie.api.builder.KieBuilder;
import org.kie.api.builder.KieFileSystem;
import org.kie.api.builder.Message;
import org.kie.api.builder.ReleaseId;
import org.kie.api.builder.Results;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;

public class Driver {

  public static final void main(String[] args) {
    try {
      KieServices kieServices = KieServices.Factory.get();
      KieFileSystem kfs = kieServices.newKieFileSystem();

      String ruleFilePath = "src/main/resources/rules/ruleFile1.drl";
      FileInputStream fis = null;
      try {
        fis = new FileInputStream(ruleFilePath);
      } catch (FileNotFoundException e) {
        e.printStackTrace();
      }
      kfs = kfs.write(ruleFilePath, kieServices.getResources().newInputStreamResource(fis));

      KieBuilder kieBuilder = kieServices.newKieBuilder(kfs).buildAll();
      Results results = kieBuilder.getResults();
      if (results.hasMessages(Message.Level.ERROR)) {
        System.out.println("~~ERROR~~:");
        System.out.println(results.getMessages());
        throw new IllegalStateException("### errors ###");
      }

      ReleaseId releaseId1 = kieServices.newReleaseId("org.default", "artifact", "1.0.0-SNAPSHOT");
      KieContainer kieContainer = kieServices.newKieContainer(releaseId1);
      KieBase kieBase = kieContainer.newKieBase(kieServices.newKieBaseConfiguration());

      KieSession kSession = kieBase.newKieSession();
      String s = "hello";
      kSession.insert(s);
      kSession.fireAllRules();

      // I edit the rule file manually at this point.
      System.out.println("Waiting");
      Thread.sleep(5000);

      ReleaseId releaseId2 = kieServices.newReleaseId("org.default", "artifact", "1.0.1-SNAPSHOT");
      kieContainer.updateToVersion(releaseId2);
      kSession.fireAllRules();

      System.out.println("Bye");
    } catch (Throwable t) {
      t.printStackTrace();
    }
  }
}

ruleFile1.drl ：

package app1;

rule "rule1"
when
    s: String()
then
    System.out.println("In rule - " + drools.getRule().getName());
    System.out.println("s = " + s);
end

我得到的输出是：

In rule - rule1
s = hello
Waiting
java.lang.NullPointerException
  at org.drools.compiler.kie.util.ChangeSetBuilder.build(ChangeSetBuilder.java:53)
  at org.drools.compiler.kie.builder.impl.KieContainerImpl.update(KieContainerImpl.java:129)
  at org.drools.compiler.kie.builder.impl.KieContainerImpl.updateToVersion(KieContainerImpl.java:106)
  at app1.Driver.main(Driver.java:54)

我还阅读this code并注意到它正在使用这样的代码将新规则文件动态添加到KieSession：

KnowledgeBase kbase = SerializationHelper.serializeObject( loadKnowledgeBase( "test_Dynamic1.drl" ) );
Collection<KnowledgePackage> kpkgs = SerializationHelper.serializeObject( loadKnowledgePackages( "test_Dynamic2.drl" ) );
kbase.addKnowledgePackages(kpkgs);

但问题是KnowledgeBase是内部API，不会向最终用户公开。

我正在使用Drools 6.2.0。

修改

我发现也许KieScanner可以用来达到我想要的效果。但我无法找到一个正确的示例来描述使用KieScanner添加新规则文件或替换现有规则文件。

This answer包含一些有用的信息，但我无法正确理解它。此外，我更喜欢内存罐。

将新规则文件添加到现有知识会话

0 个答案: