java.lang.NoClassDefFoundError: org/antlr/runtime/CharStream
at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:292)
at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:457)
at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:30)
at com.sample.DroolsTest.readKnowledgeBase(DroolsTest.java:40)
at com.sample.DroolsTest.main(DroolsTest.java:23)
解决办法：
把drools自带的antlr包加进去就ok了
对于5.0版本：
Drools 5.0.0.M4\drools-5.0.0.M4-bin\lib\antlr-runtime-3.1.1.jar