struts2小白问题
我是一刚刚开始自学struts2的小白 自己写了一小段代码，一直有错误不知道怎么调 请各位帮忙
错误提示：
Struts Problem Report
Struts has detected an unhandled exception:
# Messages: Unable to instantiate Action, userData.action.UserAction, defined for 'execute' in namespace '/'null
File: userData/action/UserAction.java
Line number: 11
Stacktraces
Unable to instantiate Action, userData.action.UserAction, defined for 'execute' in namespace '/'null
com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:318)
com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:399)
com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:198)
org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:475)
org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
java.lang.Thread.run(Thread.java:662)
java.lang.NullPointerException
userData.action.UserAction.(UserAction.java:11)
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
java.lang.reflect.Constructor.newInstance(Constructor.java:513)
java.lang.Class.newInstance0(Class.java:355)
java.lang.Class.newInstance(Class.java:308)
com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:130)
com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:161)
com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:150)
com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:120)
com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:299)
com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:399)
com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:198)
org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:475)
org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
java.lang.Thread.run(Thread.java:662)
struts.xml：
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"><struts> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="true" /> <package name="query" extends="struts-default" namespace = "/"> <default-action-ref name="index" /> <action name="index" class = "userData.action.UserAction" method = "index"> <result>/index.jsp</result> </action> <action name = "execute" class = "userData.action.UserAction" method = "execute"> <result>/query.jsp</result> </action> </package> <!-- Add packages here --></struts>
<?xml version="1.0" encoding="UTF-8"?><web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>Struts Blank</display-name> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
package userData.action;import java.util.*;import com.opensymphony.xwork2.ActionSupport;public class UserAction extends ActionSupport{ public ArrayList<UserBean> users = null; public UserBean user = null; public UserAction() { users.add(new UserBean(1)); users.add(new UserBean(2)); users.add(new UserBean(3)); users.add(new UserBean(4)); users.add(new UserBean(5)); } public ArrayList<UserBean> getUsers() { return users; } public void setUsers(ArrayList<UserBean> users) { this.users = users; } public UserBean getUser() { return user; } public void setUser(UserBean user) { this.user = user; } public String index(){ return SUCCESS; } public String execute(){ return SUCCESS; }}
package userData.action;public class UserBean { public String userId = null; public String userName = null; public String userEmail = null; public UserBean(int i){ this.userId = String.valueOf(i); this.userName = "user"+String.valueOf(i); this.userEmail = "user"+String.valueOf(i)+"@163.cmo"; } public String getUserId() { return userId; } public void setUserId(String userId) { this.userId = userId; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserEmail() { return userEmail; } public void setUserEmail(String userEmail) { this.userEmail = userEmail; }}