JBPM4项目和tomcat6.0的兼容有关问题

jbpm4在使用tomcat5.5时，没有问题，但是当使用tomcat6时就会报错。

javax.servlet.ServletException: 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/OnDuty/wfmanage_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.jasper.servlet.JspServlet.service(JspServlet.java:275)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

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/OnDuty/wfmanage_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.OnDuty.wfmanage_jsp._jspInit(wfmanage_jsp.java:27)
	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)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

?在网上搜索，发现大家都有这个问题：

引用：http://www.cnblogs.com/leshem/archive/2009/09/28/1575792.html

原因是项目中WEB-INF\lib中的三个jar包(juel.jar(在JBPM4.4中是juel-api.jar), juel-engine.jar, juel-impl.jar)和tomcat6下lib中jar包(el-api.jar)冲突

解决方法：

方法一：换成tomcat5.5 一点问题也没有了

方法二：将juel.jar(在JBPM4.4中是juel-api.jar), juel-engine.jar, juel-impl.jar这三个包复制到tomcat6下lib中，并删除原来的el-api.jar，切记要把WEB-INF\lib中的juel.jar(在JBPM4.4中是juel-api.jar), juel-engine.jar, juel-impl.jar删除。不然还是要冲突。