无法启动Struts2 - 添加过滤器无法正常工作

Question

我正在开始struts2。我在web.xml中创建了struts2的过滤条目。当我启动服务器时，它没有启动。但是当我删除条目时，它的工作。我包括了commons-io，commons-logging，struts core，ognl，freemarker jars。这是我的web.xml

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns="http://xmlns.jcp.org/xml/ns/javaee" 
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee 
http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" 
version="3.1">
 <display-name>Struts2</display-name>
 <welcome-file-list>

 <welcome-file>default.jsp</welcome-file>
</welcome-file-list>
 <filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

</web-app>

错误控制台

SEVERE: Failed to destroy end point associated with ProtocolHandler ["ajp-nio-8009"]
 java.lang.NullPointerException
at org.apache.tomcat.util.net.NioEndpoint.releaseCaches(NioEndpoint.java:316)
at org.apache.tomcat.util.net.NioEndpoint.unbind(NioEndpoint.java:492)
at org.apache.tomcat.util.net.AbstractEndpoint.destroy(AbstractEndpoint.java:821)
at org.apache.coyote.AbstractProtocol.destroy(AbstractProtocol.java:534)
at org.apache.catalina.connector.Connector.destroyInternal(Connector.java:1023)
at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:297)
at org.apache.catalina.core.StandardService.destroyInternal(StandardService.java:589)
at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:297)
at org.apache.catalina.core.StandardServer.destroyInternal(StandardServer.java:877)
at org.apache.catalina.util.LifecycleBase.destroy(LifecycleBase.java:297)
at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:351)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:485)

这可能是什么问题？