[xwiki-users] How to startup XWiki-8.4.2 with Centos-7 and Tomcat-7?

How to startup XWiki-8.4.2 with Centos-7 and Tomcat-7? I downloaded a .WAR version package of XWiki-8.4.2 under Centos-7. And run it with Tomcat-7 The servlet always cannot be initialized: Package versions: tomcat-7.0.69-10.el7.noarch java-1.8.0-openjdk-1.8.0.111-1.b15.el7_2.x86_64 The error message is below: #] cat localhost.2016-12-13.log Dec 13, 2016 6:59:06 PM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Servlet.service() for servlet [action] in context with path [/xwiki] threw exception javax.servlet.UnavailableException: Cannot initialize RequestProcessor of class com.xpn.xwiki.web.XWikiRequestProcessor: java.lang.NullPointerException at org.apache.struts.action.ActionServlet.getRequestProcessor(ActionServlet.java:614) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1910) at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449) at javax.servlet.http.HttpServlet.service(HttpServlet.java:624) at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:112) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.xwiki.wysiwyg.server.filter.ConversionFilter.doFilter(ConversionFilter.java:127) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:136) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:436) at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:190) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745) Dec 13, 2016 6:59:06 PM org.apache.catalina.core.ApplicationContext log INFO: Marking servlet action as unavailable Dec 13, 2016 6:59:06 PM org.apache.catalina.core.ApplicationContext log INFO: Marking servlet action as unavailable Dec 13, 2016 6:59:06 PM org.apache.catalina.core.ApplicationDispatcher invoke WARNING: Servlet action is currently unavailable Dec 13, 2016 6:59:06 PM org.apache.catalina.core.ApplicationDispatcher invoke WARNING: Servlet action is currently unavailable Dec 13, 2016 6:59:14 PM org.apache.catalina.core.ApplicationDispatcher invoke WARNING: Servlet action is currently unavailable Dec 13, 2016 7:00:34 PM org.apache.catalina.core.ApplicationDispatcher invoke WARNING: Servlet action is currently unavailable -- Kirby Zhou - 分机2557