错误 loader constraint violation: when resolving interface method "javax.servlet.jsp.JspApplicat

Servlet.service() for servlet jsp threw exception

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

 at org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)

 at org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)

 at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)

 at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)

 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)

 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)

 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)

 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)

 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)

 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)

 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)

 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)

 at java.lang.Thread.run(Thread.java:619)

这是网络上的说法：

jbpm4 在tomcat6 下面ssh2 这个错误！原因是项目中WEB-INF/lib中的三个jar包(juel.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, 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,
juel-engine.jar, juel-impl.jar删除。不然还是要冲突。 

      可是这个方法在我这边并不适用，其实归根结底就是jar包中类的冲突，因为我是把maven项目中的jar包直接复制到web项目的，可是发现里面的javax.el-api.jar与JAVAEE6中的java.servlet.jsp.jar冲突了，所以才引发这个异常的出现。

如果大家也遇到这样的异常只要看看你的javax.el的jar包是否与你导入的jar包冲突就可以解决好了。