1.过滤器和拦截器的区别

过滤器(Filter)：可以拦截html、jsp、servlet等各种路径。

拦截器(Interceptor)：只能拦截Action。

2. Servlet 和 Action的区别

Servlet：默认在第一次访问时创建Servlet对象，单实例。

Action：每次访问都会创建对象，多实例。

3.自定义拦截器

实现MethodFilterInterceptor接口，重写doIntercept()

myAction.java

package zh.action.demo;

import com.opensymphony.xwork2.ActionSupport;

public class MyAction extends ActionSupport{

	public String fun1(){
		System.out.println("MyAction...fun1...");
		return SUCCESS;
	}

	public String fun2(){
		System.out.println("MyAction...fun2...");
		return SUCCESS;
	}
	
	
	public String fun3(){
		System.out.println("MyAction...fun3...");
		return SUCCESS;
	}

}

myInterceptor.java

package zh.action.demo;

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

public class MyInterceptor extends MethodFilterInterceptor{

	/**
	 * 实现MethodFilterInterceptor接口，重写抽象方法
	 */
	@Override
	protected String doIntercept(ActionInvocation invocation) throws Exception {
		
		System.out.println("我是拦截器MyInterceptor!!!");
		return invocation.invoke();// 此方法返回值为"success"
		
	}

}

struts.xml

<?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>

	<constant name="struts.i18n.encoding" value="UTF-8"></constant>
	
	<package name="demo1" namespace="/" extends="struts-default">
		<!-- 声明拦截器 -->
		<interceptors>
			<interceptor name="myInterceptor" class="zh.action.demo.MyInterceptor"></interceptor>
		</interceptors>
		
		<action name="myAction_*" class="zh.action.demo.MyAction" method="{1}">
			<!-- 注册拦截器，并配置不拦截的方法 -->
			<interceptor-ref name="myInterceptor">
				<param name="excludeMethods">fun1,fun2</param>
			</interceptor-ref>
			<!-- 注册了自定义拦截器，就不会执行默认拦截器，因此需要添加默认拦截器栈 -->
			<interceptor-ref name="defaultStack"></interceptor-ref>
			<!-- 配置结果视图页面，方式为 转发 -->
			<result name="success" type="dispatcher">/interceptor.jsp</result>
		</action>
	</package>
	
</struts>

interceptor.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h1 style="color:orange;">嗨！正在学习Struts2...</h1>
</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>	
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  
 <!--  配置Struts的拦截器 -->
  <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>
  
</web-app>

访问：http://localhost:8080/Struts1/myAction_fun1.action，fun1方法不被拦截。

先在控制台输出：