java.lang.LinkageError

在学习jbpm时，出现如下异常：java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicationContext.getExpressionFactory()Ljavax/el/ExpressionFactory;" the class loader (instance of org/apache/jasper/servlet/JasperLoader) of the current class, org/apache/jsp/index_jsp, and the class loader (instance of org/apache/catalina/loader/StandardClassLoader) for resolved class, javax/servlet/jsp/JspApplicationContext, have different Class objects for the type javax/el/ExpressionFactory used in the signature
造成以上异常的主要原因的是jsp解析包冲突，不知道用哪个jar包进行解析。
解决方案如下：
1. 删除你项目中WEB-INF/lib目录下的三个jar包（juel.jar, juel-engine.jar, juel-impl.jar ）。

2. 将三个jar包（juel.jar, juel-engine.jar, juel-impl.jar ）拷贝到${tomcate 1.6}/lib目录下。