第一次部署Struts2时出现错误java.lang.ClassNotFoundException:org.apache.str

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:529)
at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:511)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:139)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4809)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5485)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
七月 27, 2016 8:46:28 上午 org.apache.catalina.core.StandardContext startInternal
SEVERE: Error filterStart
七月 27, 2016 8:46:28 上午 org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [/MyfirstStruts2] startup failed due to previous errors
七月 27, 2016 8:46:28 上午 org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
七月 27, 2016 8:46:28 上午 org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
七月 27, 2016 8:46:28 上午 org.apache.catalina.startup.Catalina start
INFO: Server startup in 1334 ms

here is the web.xml I am using!

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" >
<display-name>MyfirstStruts2</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<filter>
  <filter-name>struts2</filter-name>
  <filter-class> org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.class
  </filter-class>
</filter>
<filter-mapping>
  <filter-name>struts2</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>

问题分析和解决：

我已经将Struts2的包放到了WebInfo下的lib下，他会自动添加，不用手动BuildPath。后来发现filter-class下的包名我是通过copy qualified name的方式，本以为不会错，事实上也没有错，只是他会把".class"给添加进来，删除".class"，bug解决。