struts 自定义拦截器 用户登录拦截

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;


/**
 * 登录验证拦截器
 *
 */
@SuppressWarnings("serial")
public class LoginInteceptor implements Interceptor {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

    @Override
    public void init() {
        // TODO Auto-generated method stub

    }

    /**每次访问Action类之前，先执行intercept方法*/
    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        //获取当前访问Action的URL
        String actionName = invocation.getProxy().getActionName();
        //如果当前访问Action的URL是"loginAction_login"表示此时还没有Sesion，需要放行
        if(!"loginAction_login".equals(actionName)){
            //从Session中获取当前用户对象
            Employee employee = SessionContext.get();
            //如果Session不存在，跳转到登录页面
            if(employee==null){
                return "login";
            }
        }
        //放行，访问Action类中方法
        return invocation.invoke();
        
    }

}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
    <!-- 配置模式为开发模式，自动加载struts.xml和显示错误提示信息 -->
    <constant name="struts.devMode" value="true" />
    <!-- 设置页面主题为简单主题，去掉struts2开发提供的样式 -->
    <constant name="struts.ui.theme" value="simple" />

    <package name="default" namespace="/" extends="struts-default">
        <!-- 拦截器配置 -->
        <interceptors>
            <!-- 定义了一个用于拦截器登录的拦截器 -->
            <interceptor name="loginInterceptor" class="cn.itcast.ssh.utils.LoginInteceptor"></interceptor>
            <!-- 定义一个拦截器栈 -->
            <interceptor-stack name="systemStack">
                <interceptor-ref name="defaultStack" />
                <interceptor-ref name="loginInterceptor" />
            </interceptor-stack>
        </interceptors>
    
          <!-- 定义系统默认拦截器 全局 -->
        <default-interceptor-ref name="systemStack" /> 
        <!-- 全局结果视图 -->
        <global-results>
            <result name="login" type="redirect">
                login.jsp
            </result>
        </global-results>
        
        <action name="loginAction_*" class="loginAction" method="{1}">
            <result name="success">WEB-INF/views/main.jsp</result>
            <result name="top">WEB-INF/views/top.jsp</result>
            <result name="left">WEB-INF/views/left.jsp</result>
            <result name="welcome">WEB-INF/views/welcome.jsp</result>
        </action>
        
        <action name="leaveBillAction_*" class="leaveBillAction" method="{1}">
            <result name="home">WEB-INF/views/leaveBill/list.jsp</result>
            <result name="input">WEB-INF/views/leaveBill/input.jsp</result>
            <result name="save" type="redirectAction">
                <param name="actionName">leaveBillAction_home.action</param>
            </result>
        </action>
        
        <action name="workflowAction_*" class="workflowAction" method="{1}">
            <result name="list" type="redirectAction">
                <param name="actionName">workflowAction_deployHome.action</param>
            </result>
            <result name="deployHome">WEB-INF/views/workflow/workflow.jsp</result>
            <result name="task">WEB-INF/views/workflow/task.jsp</result>
            <result name="image">WEB-INF/views/workflow/image.jsp</result>
            <result name="listTask" type="redirectAction">
                <param name="actionName">workflowAction_listTask.action</param>
            </result>
            <result name="viewTaskForm" type="redirectAction">
                <!-- 从LeaveBill.bpmn文件中获取任务节点的url连接  workflowAction_audit.action?id= -->
                <param name="actionName">/${#url}</param>
            </result>
            <result name="taskForm">WEB-INF/views/workflow/taskForm.jsp</result>
            <result name="viewHisComment">WEB-INF/views/workflow/taskFormHis.jsp</result>
        </action>
    </package>
</struts>