Disable execution of an Interceptor

Question

I am working on Struts 2. During the implementation of an Interceptor, I came across to a question:

is it possible to stop the execution of an Interceptor all together via configuration or any other way ?

Answer 1

There are many ways to decide when a Struts2 Action must run through an Interceptor or not... the easiest are most likely:

1. Programmatically - Interceptor Configuration

   Define the same action multiple times, each one running with a different interceptor stacks (both defined globally at package level or, like in the following example, in the action configuration itself), one containing your interceptor, the other without it:

   <action name="actionWithInterceptor" class="foo.bar.actions.MyAction">
       <interceptor-ref name="myCustomInterceptor" />
       <interceptor-ref name="defaultStack" />
       <result>/view.jsp</result>
   </action>
   
   <action name="actionWithoutInterceptor" class="foo.bar.actions.MyAction">
    <!--   <interceptor-ref name="myCustomInterceptor" /> -->
       <interceptor-ref name="defaultStack" />
       <result>/view.jsp</result>
   </action>
   

2. Programmatically - Method Filtering

   MethodFilterInterceptor is an abstract Interceptor used as a base class for interceptors that will filter execution based on method names according to specified included/excluded method lists.

   Settable parameters are as follows:

   • excludeMethods - method names to be excluded from interceptor processing
   • includeMethods - method names to be included in interceptor processing

   Extend this abstract interceptor in your custom interceptor, and define the methods that will filter the interceptor execution in the configuration . In the example, every action method named foo(), or bar(), or starting with withoutCustom like withoutCustomMethod() will avoid running the interceptor, all the other methods instead will run it :

   <interceptor-stack name="myCustomStack">
   
       <interceptor-ref name="myCustomInterceptor">
           <param name="excludeMethods">foo,bar,withoutCustom*</param>
       </interceptor-ref>
   
       <interceptor-ref name="exception"/>
       <interceptor-ref name="alias"/>
       <interceptor-ref name="params"/>
       <interceptor-ref name="servletConfig"/>
       <interceptor-ref name="prepare"/>
       <interceptor-ref name="i18n"/>
       <interceptor-ref name="chain"/>
       <interceptor-ref name="modelDriven"/>
       <interceptor-ref name="fileUpload"/>
       <interceptor-ref name="staticParams"/>
       <interceptor-ref name="params"/>
       <interceptor-ref name="conversionError"/>
       <interceptor-ref name="validation">
           <param name="excludeMethods">myValidationExcudeMethod</param>
       </interceptor-ref>
       <interceptor-ref name="workflow">
           <param name="excludeMethods">myWorkflowExcludeMethod</param>
       </interceptor-ref>
   </interceptor-stack>
   

3. Dynamically - From within the Interceptor

   Do it in the Interceptor logic, basing on

   • a request parameter:

     if (request.get(MY_REQUEST_PARAM)!=null && 
         ((String) request.get(MY_REQUEST_PARAM)[0]).equals("myVal")) { ...
     

   • a session parameter:

     if (session.get(MY_SESSION_PARAM)!=null && 
         session.get(MY_SESSION_PARAM).equals("myVal")) { ...
     

   • an Interface extended by your Action:

     if(action instanceof MyStuffAware) { ...
     

Etcetera...