Struts2 之拦截器interceptor（1）

                                                       

一.理解拦截器

1. Struts2拦截器是在访问某个Action或Action的某个方法，字段之前或之后实施拦截，并且Struts2拦截器是可插拔的，拦截器是ＡＯＰ的一种实现．

2. 拦截器栈（Interceptor Stack）。Struts2拦截器栈就是将拦截器按一定的顺序联结成一条链。在访问被拦截的方法或字段时，Struts2拦截器链中的拦截器就会按其之前定义的顺序被调用。拦截器做了很多事情，框架内部有大量的拦截器，使得我们可以方便的做很多事情

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（）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文件中将中的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

很强大吧，没有拦截器，巨大的动作量将要由我们实现

<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="cookieProvider" class="org.apache.struts2.interceptor.CookieProviderInterceptor"/>            <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="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\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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 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\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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="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\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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-ref name="debugging"/>            </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"/>

这是struts-default.xml中对拦截器的配置，一般情况下我们只要自己的默认拦截器配置配成defaultStack即可

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

拦截器栈就是拦截器的集合，更大颗粒度的拦截器。具体使用配置很容易，值得记住的就是配置默认的拦截器，上面这个配置，一旦为一个Action显示的配置了某个拦截器，默认的拦截器就不好使了，需要手动配置了。