Struts 2 interceptor stack example

Often times, same set of interceptors may apply to different action classes, for example,


<package name="default" namespace="/" extends="struts-default">
	
    <action name="checkInAction" 
	class="com.mkyong.common.action.CheckInAction" >
	<interceptor-ref name="timer"/>
        <interceptor-ref name="logger"/>
	<interceptor-ref name="defaultStack" />
	<result name="success">pages/checkIn.jsp</result>
    </action>
	
    <action name="checkOutAction" 
	class="com.mkyong.common.action.CheckOutAction" >
	<interceptor-ref name="timer"/>
        <interceptor-ref name="logger"/>
	<interceptor-ref name="defaultStack" />
	<result name="success">pages/checkOut.jsp</result>
    </action>
		
</package>

In above case, it has many duplicated works and not reusable at all.

Fortunately, Struts 2 comes with interceptor stack to allow developer to group a set of interceptors into a single unit called “stack name“, and the actions can reference it via the “stack name“.

Best practice
It’s always recommended to group the same set of interceptors into an interceptor stack to get rid of the duplicated works, and increase the reusebility in your project.

<package name="default" namespace="/" extends="struts-default">
	
     <interceptors>
       	<interceptor-stack name="defaultStackWithLog">
             <interceptor-ref name="timer"/>
             <interceptor-ref name="logger"/>
	     <interceptor-ref name="defaultStack" />
        </interceptor-stack>
    </interceptors>
		
    <action name="checkInAction" 
	class="com.mkyong.common.action.CheckInAction" >
	<interceptor-ref name="defaultStackWithLog"/>
	<result name="success">pages/checkIn.jsp</result>
    </action>
	
    <action name="checkOutAction" 
	class="com.mkyong.common.action.CheckOutAction" >
	<interceptor-ref name="defaultStackWithLog"/>
	<result name="success">pages/checkOut.jsp</result>
    </action>
		
</package>

In above updated example, declares an interceptor stack, named “defaultStackWithLog“, which includes the “timer“, “logger” and “defaultStack” interceptors, and reference it as a normal interceptor via “interceptor-ref” element.

Reference

  1. Struts 2 interceptor documentation

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mkyong
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Naveen Recent comment authors
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Naveen
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Naveen

Example code:

pages/checkIn.jsp

If we replace the above code, Is it valid one, Please guid me…

Default interceptor will call before every action, right ?
Replaced code:

pages/checkIn.jsp

Naveen
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Naveen

Please guide me, how default interceptor will work with in below tags..

 <interceptors>
       	<interceptor-stack name="defaultStackWithLog">
             <interceptor-ref name="timer"/>
             <interceptor-ref name="logger"/>
	     <interceptor-ref name="defaultStack" />
        </interceptor-stack>
    </interceptors>

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