ThrowawayController


1   /*
2    * Copyright 2002-2005 the original author or authors.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.springframework.web.servlet.mvc.throwaway;
18  
19  import org.springframework.web.servlet.ModelAndView;
20  
21  /**
22   * ThrowawayController is an alternative to Spring's default Controller interface,
23   * for executable per-request command instances that are not aware of the Servlet API.
24   * In contrast to Controller, implementing beans are not supposed to be defined as
25   * Servlet/Struts-style singletons that process a HttpServletRequest but rather as
26   * WebWork/Maverick-style prototypes that get populated with request parameters,
27   * executed to determine a view, and thrown away afterwards.
28   *
29   * <p>The main advantage of this controller programming model is that controllers
30   * are testable without HttpServletRequest/HttpServletResponse mocks, just like
31   * WebWork actions. They are still web UI workflow controllers: Spring does not
32   * aim for the arguably hard-to-achieve reusability of such controllers in non-web
33   * environments, as XWork (the generic command framework from WebWork2) does
34   * but just for ease of testing.
35   *
36   * <p>A ThrowawayController differs from the command notion of Base- or
37   * AbstractCommandController in that a ThrowawayController is an <i>executable</i>
38   * command that contains workflow logic to determine the next view to render,
39   * while BaseCommandController treats commands as plain parameter holders.
40   *
41   * <p>If binding request parameters to this controller fails, a fatal BindException
42   * will be thrown.
43   *
44   * <p>If you need access to the HttpServletRequest and/or HttpServletResponse,
45   * consider implementing Controller or deriving from AbstractCommandController.
46   * ThrowawayController is specifically intended for controllers that are not aware
47   * of the Servlet API at all. Accordingly, if you need to handle session form objects
48   * or even wizard forms, consider the corresponding Controller subclasses.
49   *
50   * @author Juergen Hoeller
51   * @since 08.12.2003
52   * @see org.springframework.web.servlet.mvc.Controller
53   * @see org.springframework.web.servlet.mvc.AbstractCommandController
54   */
55  public interface ThrowawayController {
56  
57      /**
58       * Execute this controller according to its bean properties.
59       * Gets invoked after a new instance of the controller has been populated with request
60       * parameters. Is supposed to return a ModelAndView in any case, as it is not able to
61       * generate a response itself.
62       * @return a ModelAndView to render
63       * @throws Exception in case of errors
64       */
65      ModelAndView execute() throws Exception  ;
66  
67  }
68
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