Liferay: Invoke a servlet from portlet

Goal: 

To call a servlet from portlet deployed in liferay 6.

Solution:

 Step 1: Create a servlet

 public class myServlet extends HttpServlet {

  public void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

     System.out.println ("inside servlet");

     response.sendRedirect(portal_url); //url of portal page

  }

}

myServlet.java is a simple servlet class in which service() method serves the purpose of redirecting the control back to portal page. portal_url is the actual absolute URL where the servlet should redirect after processing.

Step 2: Configuring web descriptor

Go to portlet web.xml and make an entry like below:

<servlet>
        <servlet-name>myAction</servlet-name>
        <servlet-class>com.liferay.portal.kernel.servlet.PortalDelegateServlet</servlet-class>
        <init-param>
            <param-name>servlet-class</param-name>
            <param-value>com.rdg.portlet.myServlet</param-value>
        </init-param>
        <init-param>
            <param-name>sub-context</param-name>
            <param-value>myAction</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

In the above web descriptor com.liferay.portal.kernel.servlet.PortalDelegateServlet serves to redirect any request coming to "http://localhost:8080/myAction" to service() method of com.rdg.portlet.myServlet and will redirect back to the liferay portal url.

Step 3: Creating portlet action class to redirect to the servlet

public class myPortletAction extends MVCPortlet {

  public void redirectMe(ActionRequest actionRequest,
            ActionResponse actionResponse) throws IOException, PortletException {

    actionResponse.sendRedirect("http://localhost:8080/myAction");

 }

}

So when a form is submitted to the action and control is sent to redirectMe() method, it redirects the request to "http://localhost:8080/myAction" for further processing.