action.java

webwork source

/*
 * WebWork, Web Application Framework
 *
 * Distributable under Apache license.
 * See terms of license at opensource.org
 */
package webwork.action;


/**
 *	All Actions must minimally implement this interface. It provides the
 *      execute method, which is done by actions to perform whatever their
 *      purpose is.
 *
 *	@see ActionSupport
 *	@author Rickard 謆erg ([e-mail])
 *	@version $Revision: 1.6 $
 */
public interface Action
   extends java.io.Serializable
{
   // Static --------------------------------------------------------
   // The following constants represent standard results of
   // action execution

   /**
    * The action execution was successful. Show result
    * view to the end user.
    */
   public static final String SUCCESS = "success";

   /**
    * The action execution was successful but do not
    * show a view. This is useful for actions that are
    * handling the view in another fashion like redirect.
    */
   public static final String NONE = "none";


   /**
    * The action execution was a failure.
    * Show an error view, possibly asking the
    * user to retry entering data.
    */
   public static final String ERROR = "error";

   /**
    * The action execution require more input
    * in order to succeed.
    * This result is typically used if a form
    * handling action has been executed so as
    * to provide defaults for a form. The
    * form associated with the handler should be
    * shown to the end user.
    *
    * This result is also used if the given input
    * parameters are invalid, meaning the user
    * should try providing input again.
    */
   public static final String INPUT = "input";

   /**
    * The action could not execute, since the
    * user most was not logged in. The login view
    * should be shown.
    */
   public static final String LOGIN = "login";

   // Public --------------------------------------------------------
   /**
    * This method is where the logic of the action is executed.
    * Parameters are passed by calling set-methods, or by implementing
    * the ParameterAware interface.
    *
    * @return     a string representing the logical result of the execution.
    * See constants in this interface for a list of standard result values.
    * @exception   Exception  thrown if a system level exception occurs.
    * Application level exceptions should be handled by returning
    * an error value, such as Action.ERROR.
    */
   public String execute()
      throws Exception;
}