Form Core Component submission using Custom Action Type

Hi @rsl_lucky, using servlet will be much more complicated due to the way how form component has been design. But of course it is possible. It can be done like this:

You will need to create your own Form container component that will extend /apps/core/wcm/components/form/container/v2/container and do some modification in container.html, e.g.

<!--/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ~ Copyright 2016 Adobe
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~     http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/-->
<form data-sly-use.container="com.adobe.cq.wcm.core.components.models.form.Container"
      data-sly-use.grid="com.day.cq.wcm.foundation.model.responsivegrid.ResponsiveGrid"
      method="${container.method}" action="${container.action @ addSelectors='formHandler'}" id="${container.id}" name="${container.name}"
      enctype="${container.enctype}"
      class="cmp-form ${grid.cssClass}">
    <div data-sly-test="${container.errorMessages}"
         data-sly-list.item="${container.errorMessages}"
         class="cmp-form-error">
        <p class="cmp-form-error__item">${item}</p>
    </div>
    <input type="hidden" name=":formstart" value="${resource.path}"/>
    <input type="hidden" name="_charset_" value="utf-8"/>
    <input data-sly-test="${container.redirect}" type="hidden" name=":redirect" value="${container.redirect @ extension='html'}"/>
    <sly data-sly-repeat.paragraph="${grid.paragraphs}"
         data-sly-resource="${paragraph.path @ resourceType=paragraph.resourceType, decorationTagName='div', cssClassName=paragraph.cssClass}"></sly>
    <sly data-sly-resource="${resource.path @ resourceType=container.resourceTypeForDropArea, appendPath='/*', decorationTagName='div', cssClassName='new section aem-Grid-newComponent'}"
         data-sly-test="${wcmmode.edit || wcmmode.preview}"></sly>
</form>

The change that has been done is formHandler selector has been added, so it will be included in link set inside action attribute.

Next we have servlet that will consume the request:

package com.mysite.core.servlets;

import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.servlets.HttpConstants;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.osgi.service.component.annotations.Component;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import java.io.IOException;

@Component(service = Servlet.class, property = {
    "sling.servlet.methods=" + HttpConstants.METHOD_POST,
    "sling.servlet.resourceTypes=sling/servlet/default",
    "sling.servlet.selectors=formHandler",
    "sling.servlet.extensions=html"
})
public class MyFormServlet  extends SlingAllMethodsServlet {

    @Override
    protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response)
            throws ServletException, IOException {
        System.out.println("Handling form request via servlet");
    }
}

and the last thing, you need to disable com.adobe.cq.wcm.core.components.internal.servlets.CoreFormHandlingServlet OSGi component - you can sue component disbaler functinality form ACS Commons. The main reason for that is the fact that CoreFormHandlingServlet is servlet and filter so it is run in filter chain for every request.

I think that the previous solution is a bit better, because you do not need to change what you are getting out of the box. Of course running service from jsp is not a nice solution but I think as long you will keep your business logic in some java class/service this could be acceptable.