java.lang.LinkageError: loader constraint violation: when resolving interface method

JBPM4集成到web project， Tomcat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  

    org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)  
    org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)  
    org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)  
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)  
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)  

    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)  

仔细观察上边异常提示，不难发现是由于解析jsp文件的类有两个，java不知道使用哪个解析jsp文件造成的。

 

解决方法：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。