Understanding The Struts Action Class

The Action Class is a wrapper around the business logic and is a part of Model.The purpose of using Action Class is to translate the HttpServletRequest to the business logic.To use Action we need to overwrite the execute() method and Subclass. All database/business processing are done in the Action Class.Action Class is used perform all the database related stuffs.

Using execute() methodthe ActionServlet (commad) passes the parameterized class to Action Form.Struts Framework uses execute method to forward the request to the file as per the value of the returned ActionForward object.The return type of execute method is ActionForward

How to Develop Action Class?

Action class is used to forward the TestAction.jsp. In our action classit returns ActionForward called "testAction" which is defined in the struts-config.xml file (action mapping is show later in this page). The following example called TestAction.java is the action class

package academictutorilal.net;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class TestAction extends Action
{
public ActionForward execute(
ActionMapping mapping
ActionForm form
HttpServletRequest request
HttpServletResponse response) throws Exception
{
return mapping.findForward("testAction");
}
}

Understanding Action Class

The signature of the Action Class is as follows.

public ActionForward execute(ActionMapping mapping
ActionForm form
javax.servlet.http.HttpServletRequest request
javax.servlet.http.HttpServletResponse response)
throws java.lang.Exception

Action Class is used to process the specified HTTP requestand create the corresponding HTTP response (or forward to another web component that will create it)with provision for the handling exceptions thrown by the business logic.Where and how control should be forwarded or null if the response has already completed is done with use of ActionForward instance.

Parameters of Action Class

mapping - The ActionMapping parameter used to select this instance
form - The optional ActionForm bean for this request
request - The HTTP request that we are processing
response - The HTTP response that we are creating

Throws:

Action class uses throws java.lang.Exceptionif application business logic throws an exception

Adding the Action Mapping in the struts-config.xml

To test the application we will add a link in index.jsp
<html:link page="/TestAction.do">Test the Action</html:link>

The following code under the <action-mappings> tag is used for mapping TestAction class.

Click on Test the Action link on the index page if you want to test the new applications. On the user browserthe content of TestAction.jsp should be displayed .

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