错误提示: [17:18:52.937] javax.servlet.ServletException: java.lang.NullPointerException [17:18:52.937] at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:515) [17:18:52.937] at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:419) [17:18:52.937] at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70) [17:18:52.937] at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:173) [17:18:52.937] at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229) [17:18:52.937] at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:274) [17:18:52.937] at com.caucho.server.port.TcpConnection.run(TcpConnection.java:514) [17:18:52.937] at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:520) [17:18:52.937] at com.caucho.util.ThreadPool.run(ThreadPool.java:442) [17:18:52.937] at java.lang.Thread.run(Unknown Source) [17:18:52.937] Caused by: java.lang.NullPointerException