struts2 配置

	<package name="admin" extends="struts-default" namespace="/">


		<interceptors>
			<interceptor name="loginInterceptor"
				class="com.sec.Interceptor.LoginInterceptor" />

			<interceptor-stack name="checkStack">
				<interceptor-ref name="loginInterceptor" />
				<interceptor-ref name="defaultStack" />
			</interceptor-stack>
		</interceptors>
		<action name="user" class="com.sec.action.UserAction">

			<result name="main">main.jsp</result>
			<result name="list">userListView.jsp</result>
			<result name="update_list">updateUser.jsp</result>
			<result name="input">index.jsp</result>
			<interceptor-ref name="checkStack"></interceptor-ref>

		</action>



	</package>

自定义拦截器

package com.sec.Interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
import com.sec.action.UserAction;

public class LoginInterceptor  implements Interceptor{

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

	}

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

	}

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		   System.out.println("进入拦截器");
		   // 对LoginAction不做该项拦截
	        Object action = invocation.getAction();
	        if (action instanceof UserAction) {
	            System.out.println("exit check login, because this is login action.");
	            return invocation.invoke();
	        }

		return invocation.invoke();
	}


}

附上官方文档

http://struts.apache.org/docs/interceptors.html?
http://struts.apache.org/docs/how-do-we-configure-an-interceptor-to-be-used-with-every-action.html（这里写怎么配置的例子）