直接進入正題
我們在使用開源規則引擎 Drools 的時候, 啟動的時候可能會拋出如下異常:
Caused by: java.lang.ClassCastException: cn.com.chengzi.drools.domain.cofing.DroolsAutoConfiguration$1 cannot be cast to org.drools.compiler.kie.builder.impl.InternalKieModule
at org.drools.compiler.kie.builder.impl.KieServicesImpl.newKieContainer(KieServicesImpl.java:184)
at org.drools.compiler.kie.builder.impl.KieServicesImpl.newKieContainer(KieServicesImpl.java:172)
at cn.com.chengzi.drools.domain.cofing.DroolsAutoConfiguration.kieContainer(DroolsAutoConfiguration.java:57)
at cn.com.chengzi.drools.domain.cofing.DroolsAutoConfiguration$$EnhancerBySpringCGLIB$$f73b7244.CGLIB$kieContainer$2(<generated>)
at cn.com.chengzi.drools.domain.cofing.DroolsAutoConfiguration$$EnhancerBySpringCGLIB$$f73b7244$$FastClassBySpringCGLIB$$c4bed561.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363)
at cn.com.chengzi.drools.domain.cofing.DroolsAutoConfiguration$$EnhancerBySpringCGLIB$$f73b7244.kieContainer(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
... 43 more
查看發現 KieServicesImpl 類中的 newKieContainer 發現拋出了類型轉換異常:
public KieContainer newKieContainer(String containerId, ReleaseId releaseId, ClassLoader classLoader) {
InternalKieModule kieModule = (InternalKieModule) getRepository().getKieModule(releaseId);
if (kieModule == null) {
throw new RuntimeException("Cannot find KieModule: " + releaseId);
}
if (classLoader == null) {
classLoader = kieModule.getModuleClassLoader();
}
KieProject kProject = new KieModuleKieProject( kieModule, classLoader );
if (classLoader != kProject.getClassLoader()) {
// if the new kproject has a different classloader than the original one it has to be initialized
kProject.init();
}
<span class="hljs-keyword">if</span> (containerId == <span class="hljs-literal">null</span>) {
KieContainerImpl newContainer = <span class="hljs-keyword">new</span> KieContainerImpl( UUID.randomUUID().toString(), kProject, getRepository(), releaseId );
<span class="hljs-keyword">return</span> newContainer;
}
<span class="hljs-keyword">if</span> ( kContainers.<span class="hljs-keyword">get</span>(containerId) == <span class="hljs-literal">null</span> ) {
KieContainerImpl newContainer = <span class="hljs-keyword">new</span> KieContainerImpl( containerId, kProject, getRepository(), releaseId );
KieContainer check = kContainers.putIfAbsent(containerId, newContainer);
<span class="hljs-keyword">if</span> (check == <span class="hljs-literal">null</span>) {
<span class="hljs-keyword">return</span> newContainer;
} <span class="hljs-keyword">else</span> {
newContainer.dispose();
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> IllegalStateException(<span class="hljs-string">"There's already another KieContainer created with the id "</span>+containerId);
}
} <span class="hljs-keyword">else</span> {
<span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> IllegalStateException(<span class="hljs-string">"There's already another KieContainer created with the id "</span>+containerId);
}
}
此為初始化 drl 文件時的異常, 說明我們的 drl 文件不規范, Drools 不能解析成功.
我仔細檢查了一下:
rule "read-Reading-speed"
when
$rlt:ReadingLevelTest(totalWordsNum != null,totalSecondTime != null)
$rl:ReadingLevel(readingSpeed == null)
then
$rl.setReadingSpeed($rlt.getTotalWordsNum()/$rlt.getTotalSecondTime()/60);
update($rl)
System.out.println("測評結果讀速: " + $rl.toString());
end
發現其實是因為在 then 中的 update($rl) 后沒有用分號結尾, 加上分號運行正常.
when后面每行表達式后面是不需要添加分號結尾的then后面為java代碼, 每行必須使用分號結尾, 如果我們忘記了添加分號,編譯器也會報錯題型的, 但是有一些特例, 比如Drools提供的方法update(),insert等等, 如果后面不加分號, 編譯器是不會報錯的, 但是運行的時候就會拋出解析失敗!
標題：開源規則引擎 Drools 學習筆記 之 -- 1 cannot be cast to org.drools.compiler.kie.builder.impl.InternalKieModule
作者：chengzime
地址：https://www.chengzime.com.cn/articles/2019/09/11/1568195807017.html