Struts2 运行报错

HTTP Status 500 -

type Exception report

message

descriptionThe server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: The Struts dispatcher cannot be found.  This is usually caused by using Struts tags without the associated filter. Struts tags are only usable when the request has passed through its servlet filter, which initializes the Struts dispatcher needed for this tag. - [unknown location]
root cause

The Struts dispatcher cannot be found.  This is usually caused by using Struts tags without the associated filter. Struts tags are only usable when the request has passed through its servlet filter, which initializes the Struts dispatcher needed for this tag. - [unknown location]
note The full stack traces of the exception and its root causes are available in the GlassFish Server Open Source Edition 3.1.2.2 logs.

GlassFish Server Open Source Edition 3.1.2.2

总是这个错误无法解决……