We can override Login Struts action by using Hook.

In the below example we are overriding struts action "/login/login". When a user login in Liferay "com.liferay.portlet.login.action.LoginAction" is the action class that calls.

Follow the below steps to perform the change of Struts Action:

1. Create Liferay Plugin Project of type Hook.

2. Write the below code in liferay-hook.xml to override Login Struts action

<?xml version="1.0"?>
<!DOCTYPE hook PUBLIC "-//Liferay//DTD Hook 6.2.0//EN" "http://www.liferay.com/dtd/liferay-hook&#95;6_2&#95;0.dtd">

<hook>
    <struts-action>
        <struts-action-path>/login/login</struts-action-path>
        <struts-action-impl>com.evon.action.CustomLoginAction</struts-action-impl>
    </struts-action>
</hook>

3. package com.evon.action;

import javax.portlet.ActionRequest;
import javax.portlet.ActionResponse;
import javax.portlet.PortletConfig;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;

import com.liferay.portal.kernel.struts.BaseStrutsPortletAction;
import com.liferay.portal.kernel.struts.StrutsPortletAction;

public class CustomLoginAction extends BaseStrutsPortletAction{

    @Override
    public void processAction(StrutsPortletAction originalStrutsPortletAction,
            PortletConfig portletConfig, ActionRequest actionRequest,
            ActionResponse actionResponse) throws Exception {
        /**
         * This is the custom process action
         * Once you try to login this method will be invoked
         * We can write our own logic here
         * Invoke the original struts action at the end
         */

        System.out.println("in Custom login........................");

        originalStrutsPortletAction.processAction(
                originalStrutsPortletAction, portletConfig, actionRequest,
                actionResponse);
    }

    public String render(
            StrutsPortletAction originalStrutsPortletAction,
            PortletConfig portletConfig, RenderRequest renderRequest,
            RenderResponse renderResponse)
        throws Exception {

        return originalStrutsPortletAction.render(
            null, portletConfig, renderRequest, renderResponse);

    }
}

4. Deploy the Hook and try to login, this will invoke method of CustomLoginAction class instead of default one.