最近在学习ssh，咨询个问题，请知道的指点，先谢谢。 400 请求报错 

我用的是intellij idea ,创建项目采用maven的方式快速安装了SSH，但是这时候我希望采用零配置，我需要导入Convention plugin ，我采用了maven的方式下载了与struts相同版本的插件，我的方法是这样操作的
File->project structures->Libraries ->点击上面绿色的+->From Maven->搜索Convention plugin安装后一切OK
我点击->Artifacts-> 在Available Elements 中，刚刚下载的插件右键->Put into/Web-INF/lib ，导入到lib中。
但是运行项目却一直出错。

 Unable to load configuration. - bean - jar:file:/D:/IdeaProjects/ssh/out/artifacts/ssh_war_exploded/WEB-INF/lib/struts2-core.jar!/struts-default.xml:57:72
	at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:70)
	at org.apache.struts2.dispatcher.Dispatcher.getContainer(Dispatcher.java:967)
	at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:435)
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:479)
	at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
	at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:57)
	at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:279)
	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:260)
	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4572)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5215)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:752)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:728)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
	at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1702)
	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.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
	at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
	at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
	at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:482)
	at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:431)
	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.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
	at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
	at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
	at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)
	at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)
	at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)
	at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401)
	at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)
	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 sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:324)
	at sun.rmi.transport.Transport$1.run(Transport.java:200)
	at sun.rmi.transport.Transport$1.run(Transport.java:197)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
	at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:568)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:826)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:683)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:682)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: Unable to load bean: type: class:com.opensymphony.xwork2.ObjectFactory - bean - jar:file:/D:/IdeaProjects/ssh/out/artifacts/ssh_war_exploded/WEB-INF/lib/struts2-core.jar!/struts-default.xml:57:72
	at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.register(XmlConfigurationProvider.java:247)
	at org.apache.struts2.config.StrutsXmlConfigurationProvider.register(StrutsXmlConfigurationProvider.java:102)
	at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:240)
	at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:67)
	... 53 more
Caused by: Bean type class com.opensymphony.xwork2.ObjectFactory with the name struts has already been loaded by bean - jar:file:/D:/IdeaProjects/ssh/out/artifacts/ssh_war_exploded/WEB-INF/lib/struts2-core-2.3.20.1.jar!/struts-default.xml:57:72 - bean - jar:file:/D:/IdeaProjects/ssh/out/artifacts/ssh_war_exploded/WEB-INF/lib/struts2-core.jar!/struts-default.xml:57:72
	at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.register(XmlConfigurationProvider.java:231)
	... 56 more

然后我又到官方下载了相同版本的struts-all.zip ,解压了里面的Convention plugin 然后是这样操作的
File->project structures->Modules->点击右侧绿色的+->Jars or directories ->选中Convention plugin导入。
然后，我点击->Artifacts-> 在Available Elements 中，刚刚下载的插件右键->Put into/Web-INF/lib ，导入到lib中。
这一次就Ok了，工程没有出错。
为什么会这样？我就选择了Libraries中添加Convention，但是工程总是出现上面错误，我用Modules导入官方下载的就没问题，请问这是怎么回事？