The Eclipse JDT Core jar is not in the classpath
http://msq.iteye.com/blog/683074
在操作Drools的测试例子时，Eclipse后台报以下错误：
org.drools.RuntimeDroolsException: Unable to load dialect 'org.drools.rule.builder.dialect.java.JavaDialectConfiguration:java'
at org.drools.compiler.PackageBuilderConfiguration.addDialect(PackageBuilderConfiguration.java:160)
at org.drools.compiler.PackageBuilderConfiguration.buildDialectConfigurationMap(PackageBuilderConfiguration.java:146)
at org.drools.compiler.PackageBuilderConfiguration.init(PackageBuilderConfiguration.java:121)
at org.drools.compiler.PackageBuilderConfiguration.<init>(PackageBuilderConfiguration.java:98)
at org.drools.compiler.PackageBuilder.<init>(PackageBuilder.java:124)
at org.drools.compiler.PackageBuilder.<init>(PackageBuilder.java:86)
at com.sample.DecisionTableTest.readDecisionTable(DecisionTableTest.java:58)
at com.sample.DecisionTableTest.main(DecisionTableTest.java:35)
Caused by: java.lang.RuntimeException: The Eclipse JDT Core jar is not in the classpath
at org.drools.rule.builder.dialect.java.JavaDialectConfiguration.setCompiler(JavaDialectConfiguration.java:91)
at org.drools.rule.builder.dialect.java.JavaDialectConfiguration.init(JavaDialectConfiguration.java:52)
at org.drools.compiler.PackageBuilderConfiguration.addDialect(PackageBuilderConfiguration.java:156)
... 7 more
主要是缺少一个jar包：org.eclipse.jdt.core_3.3.1.v_780_R33x.jar而引起的。
Drools报错: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)
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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
＝＝＝＝＝＝＝＝＝
class not found:org/mvel2/integration/VariableResolverFactory
加入包mvel2.java