001/*
002 * Copyright 2002-2012 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.portlet.mvc;
018
019import javax.portlet.ActionRequest;
020import javax.portlet.ActionResponse;
021import javax.portlet.RenderRequest;
022import javax.portlet.RenderResponse;
023
024import org.springframework.web.portlet.ModelAndView;
025
026/**
027 * Base portlet Controller interface, representing a component that receives
028 * RenderRequest/RenderResponse and ActionRequest/ActionResponse like a
029 * {@code Portlet} but is able to participate in an MVC workflow.
030 *
031 * <p>Any implementation of the portlet Controller interface should be a
032 * <i>reusable, threadsafe</i> class, capable of handling multiple
033 * portlet requests throughout the lifecycle of an application. To be able to
034 * configure Controller(s) in an easy way, Controllers are usually JavaBeans.</p>
035 *
036 * <p><b><a name="workflow">Workflow</a>:</b></p>
037 *
038 * <p>After the DispatcherPortlet has received a request and has done its work
039 * to resolve locales, themes and suchlike, it tries to resolve a
040 * Controller to handle that request, using a
041 * {@link org.springframework.web.portlet.HandlerMapping HandlerMapping}.
042 * When a Controller has been found, the
043 * {@link #handleRenderRequest handleRenderRequest} or {@link #handleActionRequest handleActionRequest}
044 * method will be invoked, which is responsible for handling the actual
045 * request and - if applicable - returning an appropriate ModelAndView.
046 * So actually, these method are the main entrypoint for the
047 * {@link org.springframework.web.portlet.DispatcherPortlet DispatcherPortlet}
048 * which delegates requests to controllers.</p>
049 *
050 * <p>So basically any <i>direct</i> implementation of the Controller interface
051 * just handles RenderRequests/ActionRequests and should return a ModelAndView, to be
052 * further used by the DispatcherPortlet. Any additional functionality such as
053 * optional validation, form handling, etc should be obtained through extending
054 * one of the abstract controller classes mentioned above.</p>
055 *
056 * @author William G. Thompson, Jr.
057 * @author John A. Lewis
058 * @since 2.0
059 * @see ResourceAwareController
060 * @see EventAwareController
061 * @see SimpleControllerHandlerAdapter
062 * @see AbstractController
063 * @see org.springframework.web.portlet.context.PortletContextAware
064 */
065public interface Controller {
066
067        /**
068         * Process the action request. There is nothing to return.
069         * @param request current portlet action request
070         * @param response current portlet action response
071         * @throws Exception in case of errors
072         */
073        void handleActionRequest(ActionRequest request, ActionResponse response) throws Exception;
074
075        /**
076         * Process the render request and return a ModelAndView object which the DispatcherPortlet
077         * will render. A {@code null} return value is not an error: It indicates that this
078         * object completed request processing itself, thus there is no ModelAndView to render.
079         * @param request current portlet render request
080         * @param response current portlet render response
081         * @return a ModelAndView to render, or null if handled directly
082         * @throws Exception in case of errors
083         */
084        ModelAndView handleRenderRequest(RenderRequest request, RenderResponse response) throws Exception;
085
086}