拦截器没有起作用 帮我看下是什么问题

小弟初学拦截器 现做了个登录拦截器 没起作用 帮我看下 少什么东西
[code="java"]
struts.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">

<package name="authority" extends="struts-default">
    <interceptors>
        <interceptor name="authority" class="com.dg.util.common.LoginInterceptor" />
        <interceptor-stack name="mydefault">
            <interceptor-ref name="defaultStack"></interceptor-ref>
            <interceptor-ref name="authority">
            </interceptor-ref>
        </interceptor-stack>
    </interceptors>
    <default-interceptor-ref name="mydefault"></default-interceptor-ref>
    <global-results>
        <result name="input" type="redirect">/login.jsp</result>
    </global-results>
</package>
<include file="struts-sys.xml"></include>
<include file="struts-equ.xml"></include>
<include file="struts-equtest.xml"></include>
<include file="struts-equrepair.xml"></include>

[/code]
[code="java"]
LoginInterceptor.java
package com.dg.util.common;

import java.util.Map;
import com.dg.dtjc.sys.user.vo.TblUser;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

public class LoginInterceptor extends AbstractInterceptor {

@Override
public String intercept(ActionInvocation invocation) throws Exception {
    Map session =invocation.getInvocationContext().getSession();
    TblUser tu= (TblUser) session.get("tu");

    if(null!=tu){
        System.out.println(tu.getLoginname()+tu.getPassword()+"uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu");//
        return invocation.invoke();
    }else{
        return Action.INPUT;
    }
}

}
[/code]
我不登陆直接访问jsp页面 就可以进去

放在的前面：