按着正确的（基于ssh）工程修改后发生404异常，代码贴出求帮助

package cn.tmen.action;import cn.tmen.action.base.UserBaseAction;import cn.tmen.domain.Administrator;import cn.tmen.domain.Student;import cn.tmen.domain.Teacher;import static cn.tmen.service.UserService.LOGIN_ADM;import static cn.tmen.service.UserService.LOGIN_STU;import static cn.tmen.service.UserService.LOGIN_TEA;public class LoginAction extends UserBaseAction {        //定义一个常量作为学生登录成功的Result名    private final String STU_RESULT = "stu";    //定义一个常量作为教师登录成功的Result名    private final String TEA_RESULT = "tea";    //定义一个常量作为管理员登录成功的Result名        private final String ADMIN_RESULT = "admin";        private Student stu;    private Teacher tea;    private Administrator admin;    //处理登录后的提示信息    private String tip;        private String name;    private String pass;        public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPass() {        return pass;    }    public void setPass(String pass) {        this.pass = pass;    }    public Student getStu() {        return stu;    }    public void setStu(Student stu) {        this.stu = stu;    }    public Teacher getTea() {        return tea;    }    public void setTea(Teacher tea) {        this.tea = tea;    }    public Administrator getAdmin() {        return admin;    }    public void setAdmin(Administrator admin) {        this.admin = admin;    }    public String getTip() {        return tip;    }    public void setTip(String tip) {        this.tip = tip;    }    public String execute() throws Exception {                // ActionContext ctx = ActionContext.getContext();        //        // String name = (String) ctx.getSession().get("name");        // String pass = (String) ctx.getSession().get("pass");                int result = user.validLogin(getName(), getPass());                if(result==LOGIN_STU){            setTip("您已经成功登录系统");            return STU_RESULT;        }        else if(result == LOGIN_TEA){            setTip("您已经成功登录系统");            return TEA_RESULT;        }        else if(result == LOGIN_ADM){            setTip("您已经成功登录系统");            return ADMIN_RESULT;        }        else {            setTip("用户名与密码不匹配");            return ERROR;        }    }}

package cn.tmen.action.base;import cn.tmen.service.UserService;import com.opensymphony.xwork2.ActionSupport;public class UserBaseAction extends ActionSupport {    protected UserService user;    public UserService getUser() {        return user;    }    public void setUser(UserService user) {        this.user = user;    }}

<?xml version="1.0" encoding="GBK"?><!-- 指定Struts2配置文件的DTD信息 --><!DOCTYPE struts PUBLIC    "-//Apache Software Foundation//DTD Struts Configuration 2.1.7//EN"    "http://struts.apache.org/dtds/struts-2.1.7.dtd"><!-- Struts2配置文件的根元素 --><struts>    <!-- 配置了系列常量 -->    <constant name="struts.custom.i18n.resources" value="resource"/>    <constant name="struts.i18n.encoding" value="GBK"/>    <constant name="struts.devMode" value="true"/>        <package name="default" extends="struts-default">            <!-- 定义处理登录系统的Action -->    <action name="processLogin"        class="cn.tmen.action.LoginAction">        <result name="input">/WEB-INF/content/login.jsp</result>        <result name="stu">/WEB-INF/content/student/index.jsp</result>        <result name="tea">/WEB-INF/content/teacher/index.jsp</result>        <result name="admin">/WEB-INF/content/administrator/index.jsp</result>        <result name="error">/WEB-INF/content/login.jsp</result>            </action>    </package>    </struts>