Overriding and Adding Struts Actions

Do you want to add a new Struts action to Liferay portal or override existing Struts actions? Struts action hooks let you do just that.

Let’s consider the interfaces used for Struts actions. There are two:

• com.liferay.portal.kernel.struts.StrutsAction
• com.liferay.portal.kernel.struts.StrutsPortletAction

The StrutsAction interface is for regular Struts actions from the portal, like /c/portal/update_email_address. The StrutsPortletAction interface is used for similar Struts actions, but from portlets.

Struts actions are defined as classes, and they’re all connected in a struts-config.xml file. A struts-config.xml for Liferay portal running on Apache Tomcat is in the liferay-portal-[version]/tomcat-[version]/webapps/ROOT/WEB-INF directory. The struts-config.xml file links actions to specific JSP pages. Each action performs a specific task and then returns a forward, an object containing a name and path. The forward defines what page the user goes to after the action completes. When a user submits a form that maps to one of these actions, the action class is loaded, executed, and returns a forward.

A Struts action hook can wrap or override existing Struts actions or create a new Struts path; we’ll demonstrate both here. We’ll override the Struts actions in the struts-config.xml using a Struts action hook to point to a custom class, then we’ll create a new Struts path: /c/portal/sample and navigate to it. Let’s get started!

First, let’s override the login portlet’s Struts action using the example-hook we created earlier in the chapter.

Here’s the current action in your portal’s struts-config.xml file:

<action path="/login/login"
    type="com.liferay.portlet.login.action.LoginAction">

    <forward
        name="portlet.login.login"
        path="portlet.login.login"
    />
    <forward
        name="portlet.login.login_redirect"
        path="portlet.login.login_redirect"
    />
</action>

1. Navigate to your example-hook/docroot/WEB-INF folder and open liferay-hook.xml.

2. Insert the following code before the closing </hook> tag:

   <struts-action>
       <struts-action-path>/portal/sample</struts-action-path>
       <struts-action-impl>
       com.liferay.sample.hook.action.ExampleStrutsAction
       </struts-action-impl>
   </struts-action>
   <struts-action>
       <struts-action-path>/login/login</struts-action-path>
       <struts-action-impl>
       com.liferay.sample.hook.action.ExampleStrutsPortletAction
       </struts-action-impl>
   </struts-action>
   

3. Create a new package com.liferay.sample.hook.action in your example-hook/docroot/WEB-INF/src folder.

4. In your new package, create a class named ExampleStrutsPortletAction, which will wrap the login portlet Struts action. Insert the following code:

   package com.liferay.sample.hook.action;
   
   import com.liferay.portal.kernel.struts.BaseStrutsPortletAction;
   import com.liferay.portal.kernel.struts.StrutsPortletAction;
   import com.liferay.portal.theme.ThemeDisplay;
   import com.liferay.portal.kernel.util.WebKeys;
   import javax.portlet.ActionRequest;
   import javax.portlet.ActionResponse;
   import javax.portlet.PortletConfig;
   import javax.portlet.RenderRequest;
   import javax.portlet.RenderResponse;
   import javax.portlet.ResourceRequest;
   import javax.portlet.ResourceResponse;
   
   public class ExampleStrutsPortletAction extends BaseStrutsPortletAction {
   
       public void processAction(
               StrutsPortletAction originalStrutsPortletAction,
               PortletConfig portletConfig, ActionRequest actionRequest,
               ActionResponse actionResponse)
           throws Exception {
           ThemeDisplay themeDisplay =
               (ThemeDisplay)actionRequest.getAttribute(WebKeys.THEME_DISPLAY);
   
           Long currentuser = themeDisplay.getUserId();
   
           if (currentuser != null) {
               System.out.println("Wrapped /login/ action2");
   
           }
           originalStrutsPortletAction.processAction(
               originalStrutsPortletAction, portletConfig, actionRequest,
               actionResponse);
       }
   
       public String render(
               StrutsPortletAction originalStrutsPortletAction,
               PortletConfig portletConfig, RenderRequest renderRequest,
               RenderResponse renderResponse)
           throws Exception {
   
           System.out.println("Wrapped /login/ action");
   
           return originalStrutsPortletAction.render(
               null, portletConfig, renderRequest, renderResponse);
   
       }
   
       public void serveResource(
               StrutsPortletAction originalStrutsPortletAction,
               PortletConfig portletConfig, ResourceRequest resourceRequest,
               ResourceResponse resourceResponse)
           throws Exception {
   
           originalStrutsPortletAction.serveResource(
               originalStrutsPortletAction, portletConfig, resourceRequest,
               resourceResponse);
   
       }
   
   }
   

5. Create a new class named ExampleStrutsAction in the com.liferay.sample.hook.action package. It will implement your new portal Struts action. Insert the following code:

   package com.liferay.sample.hook.action;
   
   import com.liferay.portal.kernel.struts.BaseStrutsAction;
   import com.liferay.portal.kernel.util.ParamUtil;
   
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   public class ExampleStrutsAction extends BaseStrutsAction {
   
       public String execute(
           HttpServletRequest request, HttpServletResponse response)
           throws Exception {
   
           String name = ParamUtil.get(request, "name", "World");
   
           request.setAttribute("name", name);
   
           return "/portal/sample.jsp";
       }
   
   }
   

We’ve overridden the execute(HttpServletRequest, HttpServletResponse) method of BaseStrutsAction, but not the execute(StrutsAction, HttpServletRequest, HttpServletResponse) method. The original Struts action’s execute() method is ignored. That’s fine for our example.

Warning: Due to a known bug (LPS-52754), a problem can occur when overriding Struts actions with overlapping paths. Struts action paths overlap when one path is a substring of another path. The following example from Liferay’s struts-config.xml file shows three Struts action paths. Notice that the first Struts action path is a substring of each of the last two.

<action path="/document_library/edit_file_entry" ...
</action>

<action path="/document_library/edit_file_entry_discussion" ...
</action>

<action path="/document_library/edit_file_entry_type" ...
</action>

Suppose you create a hook plugin to override the /document_library/edit_file_entry path. Due to the bug mentioned above, your hook’s new, custom action is triggered not only when the intended path is invoked, but also when one of the larger, containing paths (e.g., document_library/edit_file_entry_discussion) is invoked!

To work around this issue, use the following steps:

1. Find any Struts actions with paths that contain the path of the Struts action that you are overriding.

2. If any offending paths are found, create a <struts-action> for them in your liferay-hook.xml.

3. In the class you create for each Struts action, override only the processAction, render, and serveResource methods.

4. In each overridden method, simply call the original Struts action’s method (e.g., originalStrutsPortletAction.processAction).

Best Practice: When overriding an existing Struts action, it’s usually best to override the method that takes the original Struts action handle as a parameter and execute that original Struts action. Think of the original action as a servlet filter or aspect. If you override the method that takes the original action handle as a parameter and don’t explicitly execute it, the original action won’t be executed. If you override the execute method that does not take the original action as a parameter, you are ignoring the original action and it won’t be executed.

Warning: There’s a classloading bug that manifests under certain conditions when executing an original Struts action. The issue is fixed in LPS-30162. If you don’t have the fix pack for this bug, set the context classloader to the portal classloader and execute the original action in a try block. Then, in a corresponding finally block, reset the classloader back to the original classloader.

Here’s an example for the temporary workaround:

public class SampleLayoutStrutsAction extends BaseStrutsAction {

        @Override
        public String execute(StrutsAction originalStrutsAction,
            HttpServletRequest request, HttpServletResponse response)
            throws Exception {

            System.out.println("SampleLayoutStrutsAction.execute() - " +
                request.getRequestURI());

            Thread currentThread = Thread.currentThread();

            ClassLoader contextClassLoader =
                currentThread.getContextClassLoader();

            currentThread.setContextClassLoader(
                PortalClassLoaderUtil.getClassLoader());

            try {
                return originalStrutsAction.execute(request, response);
            }
            finally {
                currentThread.setContextClassLoader(contextClassLoader);
            }
        }

    }

That’s it for overriding the Struts actions! Now Let’s get our new Struts path working.

1. Create sample.jsp in the example-hook/docroot/META-INF/custom_jsps/html/portal directory. Insert the following code:

   <%
   String name = (String)request.getAttribute("name");
   %>
   Hello <%= name %>!
   

2. Add /portal/sample to your portal’s list of paths that don’t require authentication by copying your existing auth.public.paths property assignment from your portal’s portal.properties into your portal-ext.properties file and adding /portal/sample to the end of the value list. It looks similar to the assignment below:

       auth.public.paths=\
           /asset/get_categories,\
           ...
           /wiki/rss,\
           /portal/sample
   

3. Restart your portal server.

Congratulations! Your Struts action hook plugin is complete! Now when you access the Sign In portlet, this message prints to your console:

Wrapped /login/ action

When you actually log in, this message prints to your console:

Wrapped /login/ action2
Wrapped /login/ action

Both custom Struts actions are executed via your Struts action hook!

Try your new Struts path by accessing it from your browser (e.g. http://localhost:8080/c/portal/sample).

Figure 7.6: Your new Struts action displays *Hello World!* in your browser.

Let’s continue our hooks expedition by overriding a portal service.