Struts2.2 Interceptors

AOP 中的 aspect 在不同的框架下表示的意思不同：

Java 代理：服务

Spring ： advice

Struts ：拦截器

Struts 中拦截器是 AOP （ Aspect-Oriented Programming ）思想的体现：

1 、将与业务无关的解决特定领域问题（日志、安全、事务 … ）的代码从程序流程中分离出来，以切面的方式挂载到主流程的执行点

2 、集中管理横切关注点代码

3 、提高架构分层级别

Struts2 拦截器的功能：

1 、拦截器是 Struts2 的基石；

2 、 Struts2 通过丰富的内置拦截器实现了清洁的 MVC 分层；

3 、 Struts2 的大多数功能都是通过拦截器提供的（表单数据映射，数据校验，国际化，文件上传等等）；

4 、 Struts2 允许开发者自定义拦截器（权限验证，日志，事务处理）

5 、 Struts2 插件扩展基本上都是通过拦截器实现的

拦截器机制：

1 、拦截 Action 的执行，为其添加预处理和后处理过程

2 、 ActionInvocation ， Action 调度器，实现拦截器与 Action 的 cross-cut （横切）

ActionInvocation 说明：

执行过程 :

1 、 Struts 根据请求的 URL 创建对应的 Action 对象，并为其创建 ActionInvocation 实例；

2 、根据配置文件查找应当触发的拦截器和执行顺序，并添加到 ActionInvocation 对象中；

3 、 ActionInvocation 的 invoke() 方法被触发；

逐个调用 interceptor 的 intercep() 方法

调用预处理方法

递归调用 ActionInvocation 的 invoke 方法

调用后处理方法

4 、执行 Action ，获取 result ；

5 、执行 inteceptor 中注册的 preResultListeners ；

6 、执行 Result ；

为了理解清楚，我们再看看 Action 的生命周期：

action lifecyle

Interceptors

<package name="default" extends="struts-default">
   <interceptors>
       <interceptor name="timer" class=".."/>
       <interceptor name="logger" class=".."/>
   </interceptors>

   <action name="login"
      class="tutorial.Login">
        <interceptor-ref name="timer"/>
        <interceptor-ref name="logger"/>
         <result name="input">login.jsp</result>
         <result name="success"
            type="redirectAction">/secure/home</result>
   </action>
</package>

Stacking Interceptors

拦截器栈：

拦截器栈指定包含的拦截器引用和执行顺序，便于使用

内置拦截器栈

basicStack ： Struts2 提供了最常用的栈，提供了异常处理，将 HTTP 对象和请求 / 表单参数注入 action ，和处理转换错误的功能；

validationWorkflowStack ：向 basic 栈中添加验证和工作流的功能；

fileUploadStack ：向 basic 栈中添加对自动文件上传的支持；

defaultStack ：这是默认的栈，它为绝大多数的应用场景提供了所有的功能，实际上，他包括了核心发布版中几乎所有的可用拦截器；

<package name="default" extends="struts-default">
   <interceptors>
        <interceptor name="timer" class=".."/>
        <interceptor name="logger" class=".."/>
        <interceptor-stack name="myStack">
           <interceptor-ref name="timer"/>
           <interceptor-ref name="logger"/>
        </interceptor-stack>
    </interceptors>

<action name="login"
     class="tutuorial.Login">
         <interceptor-ref name="myStack"/>
         <result name="input">login.jsp</result>
         <result name="success"
             type="redirectAction">/secure/home</result>
</action>
</package>

Demo

MyInterceptor.java

package org.lxh.interceptor;

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

/**
 * @author xudongwang 2011-5-13
 *
 */
public class MyInterceptor extends AbstractInterceptor {

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		System.out.println("拦截器之前。。。。");
		String result = invocation.invoke();
		System.out.println("拦截器之后。。。。");
		return result;
	}

}

说明：

invocation.invoke(); 传递拦截器链，即继续执行其他的拦截器

此方法返回后续拦截器执行的 result ；

在此方法前进行预处理；

在此方法后处理后处理；

Struts.xml:

        <interceptors>
		<interceptor name="myInterceptor" class="org.lxh.interceptor.MyInterceptor"></interceptor>
	</interceptors>
	<action name="hello-world" class="org.lxh.action.UserAction" method="hello">
		<interceptor-ref name="myInterceptor"></interceptor-ref>
		<result>/hello_struts2.jsp</result>
	</action>

Struts2 提供的拦截器可以在 struts2-core-2.1.8.1.jar 包下的 struts-default.xml 查看关于默认的拦截器与拦截器链的配置。

<?xml version="1.0" encoding="UTF-8" ?>
<!--
/*
 * $Id$
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
-->
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.1.7//EN"
    "http://struts.apache.org/dtds/struts-2.1.7.dtd">

<struts>
    <bean class="com.opensymphony.xwork2.ObjectFactory" name="xwork" />
    <bean type="com.opensymphony.xwork2.ObjectFactory" name="struts" class="org.apache.struts2.impl.StrutsObjectFactory" />

    <bean type="com.opensymphony.xwork2.ActionProxyFactory" name="xwork" class="com.opensymphony.xwork2.DefaultActionProxyFactory"/>
    <bean type="com.opensymphony.xwork2.ActionProxyFactory" name="struts" class="org.apache.struts2.impl.StrutsActionProxyFactory"/>

    <bean type="com.opensymphony.xwork2.conversion.ObjectTypeDeterminer" name="tiger" class="com.opensymphony.xwork2.conversion.impl.DefaultObjectTypeDeterminer"/>
    <bean type="com.opensymphony.xwork2.conversion.ObjectTypeDeterminer" name="notiger" class="com.opensymphony.xwork2.conversion.impl.DefaultObjectTypeDeterminer"/>
    <bean type="com.opensymphony.xwork2.conversion.ObjectTypeDeterminer" name="struts" class="com.opensymphony.xwork2.conversion.impl.DefaultObjectTypeDeterminer"/>

    <bean type="com.opensymphony.xwork2.util.PatternMatcher" name="struts" class="com.opensymphony.xwork2.util.WildcardHelper" />
    <bean type="com.opensymphony.xwork2.util.PatternMatcher" name="namedVariable" class="com.opensymphony.xwork2.util.NamedVariablePatternMatcher"/>
    <bean type="com.opensymphony.xwork2.util.PatternMatcher" name="regex" class="org.apache.struts2.util.RegexPatternMatcher"/>

    <bean type="org.apache.struts2.dispatcher.mapper.ActionMapper" name="struts" class="org.apache.struts2.dispatcher.mapper.DefaultActionMapper" />
    <bean type="org.apache.struts2.dispatcher.mapper.ActionMapper" name="composite" class="org.apache.struts2.dispatcher.mapper.CompositeActionMapper" />
    <bean type="org.apache.struts2.dispatcher.mapper.ActionMapper" name="restful" class="org.apache.struts2.dispatcher.mapper.RestfulActionMapper" />
    <bean type="org.apache.struts2.dispatcher.mapper.ActionMapper" name="restful2" class="org.apache.struts2.dispatcher.mapper.Restful2ActionMapper" />

    <bean type="org.apache.struts2.dispatcher.multipart.MultiPartRequest" name="struts" class="org.apache.struts2.dispatcher.multipart.JakartaMultiPartRequest" scope="default"/>
    <bean type="org.apache.struts2.dispatcher.multipart.MultiPartRequest" name="jakarta" class="org.apache.struts2.dispatcher.multipart.JakartaMultiPartRequest" scope="default" />
    <constant name="struts.multipart.handler" value="jakarta" />

    <bean type="org.apache.struts2.views.TagLibrary" name="s" class="org.apache.struts2.views.DefaultTagLibrary" />

    <bean class="org.apache.struts2.views.freemarker.FreemarkerManager" name="struts" />
    <bean class="org.apache.struts2.views.velocity.VelocityManager" name="struts" optional="true" />

    <bean class="org.apache.struts2.components.template.TemplateEngineManager" />
    <bean type="org.apache.struts2.components.template.TemplateEngine" name="ftl" class="org.apache.struts2.components.template.FreemarkerTemplateEngine" />
    <bean type="org.apache.struts2.components.template.TemplateEngine" name="vm" class="org.apache.struts2.components.template.VelocityTemplateEngine" />
    <bean type="org.apache.struts2.components.template.TemplateEngine" name="jsp" class="org.apache.struts2.components.template.JspTemplateEngine" />

    <bean type="com.opensymphony.xwork2.conversion.impl.XWorkConverter" name="struts" class="com.opensymphony.xwork2.conversion.impl.XWorkConverter" />
    <bean type="com.opensymphony.xwork2.conversion.impl.XWorkConverter" name="xwork1" class="com.opensymphony.xwork2.conversion.impl.XWorkConverter" />
    <bean class="com.opensymphony.xwork2.conversion.impl.XWorkBasicConverter" />

    <bean type="com.opensymphony.xwork2.TextProvider" name="xwork1" class="com.opensymphony.xwork2.TextProviderSupport" scope="default" />
    <bean type="com.opensymphony.xwork2.TextProvider" name="struts" class="com.opensymphony.xwork2.TextProviderSupport" scope="default" />

    <bean type="org.apache.struts2.components.UrlRenderer" name="struts" class="org.apache.struts2.components.ServletUrlRenderer"/>

    <bean type="com.opensymphony.xwork2.util.ValueStackFactory" name="struts" class="com.opensymphony.xwork2.ognl.OgnlValueStackFactory" />
    <bean type="com.opensymphony.xwork2.util.reflection.ReflectionProvider" name="struts" class="com.opensymphony.xwork2.ognl.OgnlReflectionProvider" />
    <bean type="com.opensymphony.xwork2.util.reflection.ReflectionContextFactory" name="struts" class="com.opensymphony.xwork2.ognl.OgnlReflectionContextFactory" />

    <bean type="com.opensymphony.xwork2.TextProvider" name="system" class="com.opensymphony.xwork2.DefaultTextProvider" />
    <bean type="com.opensymphony.xwork2.conversion.NullHandler" name="java.lang.Object" class="com.opensymphony.xwork2.conversion.impl.InstantiatingNullHandler" />

    <bean type="com.opensymphony.xwork2.validator.ActionValidatorManager" name="struts" class="com.opensymphony.xwork2.validator.AnnotationActionValidatorManager" />
    <bean type="com.opensymphony.xwork2.validator.ActionValidatorManager" name="no-annotations" class="com.opensymphony.xwork2.validator.DefaultActionValidatorManager" />

    <bean type="com.opensymphony.xwork2.validator.ValidatorFactory" class="com.opensymphony.xwork2.validator.DefaultValidatorFactory"/>
    <bean type="com.opensymphony.xwork2.validator.ValidatorFileParser" class="com.opensymphony.xwork2.validator.DefaultValidatorFileParser" />

    <bean class="com.opensymphony.xwork2.ognl.OgnlUtil" />

    <bean type="ognl.PropertyAccessor" name="com.opensymphony.xwork2.util.CompoundRoot" class="com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.lang.Object" class="com.opensymphony.xwork2.ognl.accessor.ObjectAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.Iterator" class="com.opensymphony.xwork2.ognl.accessor.XWorkIteratorPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.Enumeration" class="com.opensymphony.xwork2.ognl.accessor.XWorkEnumerationAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.List" class="com.opensymphony.xwork2.ognl.accessor.XWorkListPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.Set" class="com.opensymphony.xwork2.ognl.accessor.XWorkCollectionPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.Map" class="com.opensymphony.xwork2.ognl.accessor.XWorkMapPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.Collection" class="com.opensymphony.xwork2.ognl.accessor.XWorkCollectionPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="com.opensymphony.xwork2.ognl.ObjectProxy" class="com.opensymphony.xwork2.ognl.accessor.ObjectProxyPropertyAccessor" />

    <bean type="ognl.MethodAccessor" name="java.lang.Object" class="com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor" />
    <bean type="ognl.MethodAccessor" name="com.opensymphony.xwork2.util.CompoundRoot" class="com.opensymphony.xwork2.ognl.accessor.CompoundRootAccessor" />

    <bean class="org.apache.struts2.views.jsp.ui.OgnlTool" />

    <bean type="org.apache.struts2.dispatcher.StaticContentLoader" class="org.apache.struts2.dispatcher.DefaultStaticContentLoader" name="struts" />
    <bean type="com.opensymphony.xwork2.UnknownHandlerManager" class="com.opensymphony.xwork2.DefaultUnknownHandlerManager" name="struts" />

    <!--  Silly workarounds for OGNL since there is currently no way to flush its internal caches -->
    <bean type="ognl.PropertyAccessor" name="java.util.ArrayList" class="com.opensymphony.xwork2.ognl.accessor.XWorkListPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.HashSet" class="com.opensymphony.xwork2.ognl.accessor.XWorkCollectionPropertyAccessor" />
    <bean type="ognl.PropertyAccessor" name="java.util.HashMap" class="com.opensymphony.xwork2.ognl.accessor.XWorkMapPropertyAccessor" />

    <package name="struts-default" abstract="true">
        <result-types>
            <result-type name="chain" class="com.opensymphony.xwork2.ActionChainResult"/>
            <result-type name="dispatcher" class="org.apache.struts2.dispatcher.ServletDispatcherResult" default="true"/>
            <result-type name="freemarker" class="org.apache.struts2.views.freemarker.FreemarkerResult"/>
            <result-type name="httpheader" class="org.apache.struts2.dispatcher.HttpHeaderResult"/>
            <result-type name="redirect" class="org.apache.struts2.dispatcher.ServletRedirectResult"/>
            <result-type name="redirectAction" class="org.apache.struts2.dispatcher.ServletActionRedirectResult"/>
            <result-type name="stream" class="org.apache.struts2.dispatcher.StreamResult"/>
            <result-type name="velocity" class="org.apache.struts2.dispatcher.VelocityResult"/>
            <result-type name="xslt" class="org.apache.struts2.views.xslt.XSLTResult"/>
            <result-type name="plainText" class="org.apache.struts2.dispatcher.PlainTextResult" />
        </result-types>

        <interceptors>
            <interceptor name="alias" class="com.opensymphony.xwork2.interceptor.AliasInterceptor"/>
            <interceptor name="autowiring" class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>
            <interceptor name="chain" class="com.opensymphony.xwork2.interceptor.ChainingInterceptor"/>
            <interceptor name="conversionError" class="org.apache.struts2.interceptor.StrutsConversionErrorInterceptor"/>
            <interceptor name="cookie" class="org.apache.struts2.interceptor.CookieInterceptor"/>
            <interceptor name="clearSession" class="org.apache.struts2.interceptor.ClearSessionInterceptor" />
            <interceptor name="createSession" class="org.apache.struts2.interceptor.CreateSessionInterceptor" />
            <interceptor name="debugging" class="org.apache.struts2.interceptor.debugging.DebuggingInterceptor" />
            <interceptor name="execAndWait" class="org.apache.struts2.interceptor.ExecuteAndWaitInterceptor"/>
            <interceptor name="exception" class="com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor"/>
            <interceptor name="fileUpload" class="org.apache.struts2.interceptor.FileUploadInterceptor"/>
            <interceptor name="i18n" class="com.opensymphony.xwork2.interceptor.I18nInterceptor"/>
            <interceptor name="logger" class="com.opensymphony.xwork2.interceptor.LoggingInterceptor"/>
            <interceptor name="modelDriven" class="com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor"/>
            <interceptor name="scopedModelDriven" class="com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor"/>
            <interceptor name="params" class="com.opensymphony.xwork2.interceptor.ParametersInterceptor"/>
            <interceptor name="actionMappingParams" class="org.apache.struts2.interceptor.ActionMappingParametersInteceptor"/>
            <interceptor name="prepare" class="com.opensymphony.xwork2.interceptor.PrepareInterceptor"/>
            <interceptor name="staticParams" class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor"/>
            <interceptor name="scope" class="org.apache.struts2.interceptor.ScopeInterceptor"/>
            <interceptor name="servletConfig" class="org.apache.struts2.interceptor.ServletConfigInterceptor"/>
            <interceptor name="timer" class="com.opensymphony.xwork2.interceptor.TimerInterceptor"/>
            <interceptor name="token" class="org.apache.struts2.interceptor.TokenInterceptor"/>
            <interceptor name="tokenSession" class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor"/>
            <interceptor name="validation" class="org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor"/>
            <interceptor name="workflow" class="com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor"/>
            <interceptor name="store" class="org.apache.struts2.interceptor.MessageStoreInterceptor" />
            <interceptor name="checkbox" class="org.apache.struts2.interceptor.CheckboxInterceptor" />
            <interceptor name="profiling" class="org.apache.struts2.interceptor.ProfilingActivationInterceptor" />
            <interceptor name="roles" class="org.apache.struts2.interceptor.RolesInterceptor" />
            <interceptor name="jsonValidation" class="org.apache.struts2.interceptor.validation.JSONValidationInterceptor" />
            <interceptor name="annotationWorkflow" class="com.opensymphony.xwork2.interceptor.annotations.AnnotationWorkflowInterceptor" />
            <interceptor name="multiselect" class="org.apache.struts2.interceptor.MultiselectInterceptor" />

            <!-- Basic stack -->
            <interceptor-stack name="basicStack">
                <interceptor-ref name="exception"/>
                <interceptor-ref name="servletConfig"/>
                <interceptor-ref name="prepare"/>
                <interceptor-ref name="checkbox"/>
                <interceptor-ref name="multiselect"/>
                <interceptor-ref name="actionMappingParams"/>
                <interceptor-ref name="params">
                    <param name="excludeParams">dojo\..*,^struts\..*</param>
                </interceptor-ref>
                <interceptor-ref name="conversionError"/>
            </interceptor-stack>

            <!-- Sample validation and workflow stack -->
            <interceptor-stack name="validationWorkflowStack">
                <interceptor-ref name="basicStack"/>
                <interceptor-ref name="validation"/>
                <interceptor-ref name="workflow"/>
            </interceptor-stack>

            <!-- Sample JSON validation stack -->
            <interceptor-stack name="jsonValidationWorkflowStack">
                <interceptor-ref name="basicStack"/>
                <interceptor-ref name="validation">
                    <param name="excludeMethods">input,back,cancel</param>
                </interceptor-ref>
                <interceptor-ref name="jsonValidation"/>
                <interceptor-ref name="workflow"/>
            </interceptor-stack>

            <!-- Sample file upload stack -->
            <interceptor-stack name="fileUploadStack">
                <interceptor-ref name="fileUpload"/>
                <interceptor-ref name="basicStack"/>
            </interceptor-stack>

            <!-- Sample model-driven stack  -->
            <interceptor-stack name="modelDrivenStack">
                <interceptor-ref name="modelDriven"/>
                <interceptor-ref name="basicStack"/>
            </interceptor-stack>

            <!-- Sample action chaining stack -->
            <interceptor-stack name="chainStack">
                <interceptor-ref name="chain"/>
                <interceptor-ref name="basicStack"/>
            </interceptor-stack>

            <!-- Sample i18n stack -->
            <interceptor-stack name="i18nStack">
                <interceptor-ref name="i18n"/>
                <interceptor-ref name="basicStack"/>
            </interceptor-stack>

            <!-- An example of the paramsPrepareParams trick. This stack
                 is exactly the same as the defaultStack, except that it
                 includes one extra interceptor before the prepare interceptor:
                 the params interceptor.

                 This is useful for when you wish to apply parameters directly
                 to an object that you wish to load externally (such as a DAO
                 or database or service layer), but can't load that object
                 until at least the ID parameter has been loaded. By loading
                 the parameters twice, you can retrieve the object in the
                 prepare() method, allowing the second params interceptor to
                 apply the values on the object. -->
            <interceptor-stack name="paramsPrepareParamsStack">
                <interceptor-ref name="exception"/>
                <interceptor-ref name="alias"/>
                <interceptor-ref name="i18n"/>
                <interceptor-ref name="checkbox"/>
                <interceptor-ref name="multiselect"/>
                <interceptor-ref name="params">
                    <param name="excludeParams">dojo\..*,^struts\..*</param>
                </interceptor-ref>
                <interceptor-ref name="servletConfig"/>
                <interceptor-ref name="prepare"/>
                <interceptor-ref name="chain"/>
                <interceptor-ref name="modelDriven"/>
                <interceptor-ref name="fileUpload"/>
                <interceptor-ref name="staticParams"/>
                <interceptor-ref name="actionMappingParams"/>
                <interceptor-ref name="params">
                    <param name="excludeParams">dojo\..*,^struts\..*</param>
                </interceptor-ref>
                <interceptor-ref name="conversionError"/>
                <interceptor-ref name="validation">
                    <param name="excludeMethods">input,back,cancel,browse</param>
                </interceptor-ref>
                <interceptor-ref name="workflow">
                    <param name="excludeMethods">input,back,cancel,browse</param>
                </interceptor-ref>
            </interceptor-stack>

            <!-- A complete stack with all the common interceptors in place.
                 Generally, this stack should be the one you use, though it
                 may do more than you need. Also, the ordering can be
                 switched around (ex: if you wish to have your servlet-related
                 objects applied before prepare() is called, you'd need to move
                 servletConfig interceptor up.

                 This stack also excludes from the normal validation and workflow
                 the method names input, back, and cancel. These typically are
                 associated with requests that should not be validated.
                 -->
            <interceptor-stack name="defaultStack">
                <interceptor-ref name="exception"/>
                <interceptor-ref name="alias"/>
                <interceptor-ref name="servletConfig"/>
                <interceptor-ref name="i18n"/>
                <interceptor-ref name="prepare"/>
                <interceptor-ref name="chain"/>
                <interceptor-ref name="debugging"/>
                <interceptor-ref name="scopedModelDriven"/>
                <interceptor-ref name="modelDriven"/>
                <interceptor-ref name="fileUpload"/>
                <interceptor-ref name="checkbox"/>
                <interceptor-ref name="multiselect"/>
                <interceptor-ref name="staticParams"/>
                <interceptor-ref name="actionMappingParams"/>
                <interceptor-ref name="params">
                  <param name="excludeParams">dojo\..*,^struts\..*</param>
                </interceptor-ref>
                <interceptor-ref name="conversionError"/>
                <interceptor-ref name="validation">
                    <param name="excludeMethods">input,back,cancel,browse</param>
                </interceptor-ref>
                <interceptor-ref name="workflow">
                    <param name="excludeMethods">input,back,cancel,browse</param>
                </interceptor-ref>
            </interceptor-stack>

            <!-- The completeStack is here for backwards compatibility for
                 applications that still refer to the defaultStack by the
                 old name -->
            <interceptor-stack name="completeStack">
                <interceptor-ref name="defaultStack"/>
            </interceptor-stack>

            <!-- Sample execute and wait stack.
                 Note: execAndWait should always be the *last* interceptor. -->
            <interceptor-stack name="executeAndWaitStack">
                <interceptor-ref name="execAndWait">
                    <param name="excludeMethods">input,back,cancel</param>
                </interceptor-ref>
                <interceptor-ref name="defaultStack"/>
                <interceptor-ref name="execAndWait">
                    <param name="excludeMethods">input,back,cancel</param>
                </interceptor-ref>
            </interceptor-stack>

       </interceptors>

        <default-interceptor-ref name="defaultStack"/>

        <default-class-ref class="com.opensymphony.xwork2.ActionSupport" />
    </package>

</struts>

下面列一个表格简单说明一下：

拦截器	名字	说明
Alias Interceptor	alias	在不同请求之间将请求参数在不同名字件转换，请求内容不变
Chaining Interceptor	chain	让前一个 Action 的属性可以被后一个 Action 访问，现在和 chain 类型的 result （ <result type=”chain”> ）结合使用。
Checkbox Interceptor	checkbox	添加了 checkbox 自动处理代码，将没有选中的 checkbox 的内容设定为 false ，而 html 默认情况下不提交没有选中的 checkbox 。
Cookies Interceptor	cookies	使用配置的 name,value 来是指 cookies
Conversion Error Interceptor	conversionError	将错误从 ActionContext 中添加到 Action 的属性字段中。
Create Session Interceptor	createSession	自动的创建 HttpSession ，用来为需要使用到 HttpSession 的拦截器服务。
Debugging Interceptor	debugging	提供不同的调试用的页面来展现内部的数据状况。
Execute and Wait Interceptor	execAndWait	在后台执行 Action ，同时将用户带到一个中间的等待页面。
Exception Interceptor	exception	将异常定位到一个画面
File Upload Interceptor	fileUpload	提供文件上传功能
I18n Interceptor	i18n	记录用户选择的 locale
Logger Interceptor	logger	输出 Action 的名字
Message Store Interceptor	store	存储或者访问实现 ValidationAware 接口的 Action 类出现的消息，错误，字段错误等。
Model Driven Interceptor	model-driven	如果一个类实现了 ModelDriven ，将 getModel 得到的结果放在 Value Stack 中。
Scoped Model Driven	scoped-model-driven	如果一个 Action 实现了 ScopedModelDriven ，则这个拦截器会从相应的 Scope 中取出 model 调用 Action 的 setModel 方法将其放入 Action 内部。
Parameters Interceptor	params	将请求中的参数设置到 Action 中去。
Prepare Interceptor	prepare	如果 Acton 实现了 Preparable ，则该拦截器调用 Action 类的 prepare 方法。
Scope Interceptor	scope	将 Action 状态存入 session 和 application 的简单方法。
Servlet Config Interceptor	servletConfig	提供访问 HttpServletRequest 和 HttpServletResponse 的方法，以 Map 的方式访问。
Static Parameters Interceptor	staticParams	从 struts.xml 文件中将 <action> 中的 <param> 中的内容设置到对应的 Action 中。
Roles Interceptor	roles	确定用户是否具有 JAAS 指定的 Role ，否则不予执行。
Timer Interceptor	timer	输出 Action 执行的时间
Token Interceptor	token	通过 Token 来避免双击
Token Session Interceptor	tokenSession	和 Token Interceptor 一样，不过双击的时候把请求的数据存储在 Session 中
Validation Interceptor	validation	使用 action-validation.xml 文件中定义的内容校验提交的数据。
Workflow Interceptor	workflow	调用 Action 的 validate 方法，一旦有错误返回，重新定位到 INPUT 画面
Parameter Filter Interceptor	N/A	从参数列表中删除不必要的参数
Profiling Interceptor	profiling	通过参数激活 profile

ok，struts2.2的拦截器就搞这么多。

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