直接进入正题
我们在使用开源规则引擎 Drools 的时候, 启动的时候可能会抛出如下异常:
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
查看发现 KieServicesImpl 类中的 newKieContainer 发现抛出了类型转换异常:
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);
}
}
此为初始化 drl 文件时的异常, 说明我们的 drl 文件不规范, Drools 不能解析成功.
我仔细检查了一下:
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("测评结果读速: " + $rl.toString());
end
发现其实是因为在 then 中的 update($rl) 后没有用分号结尾, 加上分号运行正常.
when后面每行表达式后面是不需要添加分号结尾的then后面为java代码, 每行必须使用分号结尾, 如果我们忘记了添加分号,编译器也会报错题型的, 但是有一些特例, 比如Drools提供的方法update(),insert等等, 如果后面不加分号, 编译器是不会报错的, 但是运行的时候就会抛出解析失败!
标题：开源规则引擎 Drools 学习笔记 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