What is DispatchAction and LookupDispatchAction ?

DispatchAction

• org.apache.struts.action.DispatchAction class
• lets you combine Struts actions into one class, each with their own method.
• allows multiple operation to mapped to the different functions in the same Action class.

Example

Create action class by extending it DispatchAction class and put multiple methods into it. Like :

public ActionForward create(ActionMapping mapping,  ActionForm form, 

  HttpServletRequest request, HttpServletResponse response) 

  throws IOException, ServletException { ...}

public ActionForward save(ActionMapping mapping, ActionFormform, 

  HttpServletRequest request, HttpServletResponse response) 

  throws IOException, ServletException { ...}

Specify the name of of the dispatch property as the "parameter" property of the action-mapping.

<action path="/reg/dispatch" type="app.reg.RegDispatch" 

        name="regForm" scope= "request" validate="true"

        parameter="dispatch"/>

Now, call this action by passing request parameter "dispatch" from the calling page.

URL ? dispatch = create

URL ? dispatch = save

LookupDispatchAction

• An abstract Action that dispatches to the subclass mapped execute method.
• Useful in cases where an HTML form has multiple submit buttons with the same name.
• The button name is specified by the parameter property of the corresponding ActionMapping.

Example

Put the multiple submit buttons with same names but different messages keys (message keys defined in message resources)

<html:form action="/test">

   <html:submit property="method">

      <bean: message key="button.add"/>

    </html:submit>

    <html:submit property="method">

      <bean:message key="button.delete"/>

    </html:submit>

</html:form>

Create action class by extending it LookupDispatchAction class.

Your subclass must implement both getKeyMethodMap and the methods defined in the map.

   public ActionForward add(...)  { ... }

   public ActionForward delete(...)   { ... }

   protected Map getKeyMethodMap() {

      Map map =  new HashMap();

      map.put("button.add", "add");

      map.put("button.delete", "delete");

      return map;

   }

Specify the name of of the dispatch property as the "parameter" property of the action-mapping.

<action path="/test" type="org.example.MyAction" name="MyForm" 

        scope="request" input="/test.jsp" parameter="method"/>