HandlerAdapter


1   /*
2    * Copyright 2002-2006 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.portlet;
18  
19  import javax.portlet.ActionRequest;
20  import javax.portlet.ActionResponse;
21  import javax.portlet.RenderRequest;
22  import javax.portlet.RenderResponse;
23  
24  /**
25   * Portlet MVC framework SPI interface, allowing parameterization of core MVC workflow.
26   *
27   * <p>Interface that must be implemented for each handler type to handle a request.
28   * This interface is used to allow the DispatcherPortlet to be indefinitely
29   * extensible. The DispatcherPortlet accesses all installed handlers through this
30   * interface, meaning that it does not contain code specific to any handler type.
31   *
32   * <p>Note that a handler can be of type Object. This is to enable handlers from
33   * other frameworks to be integrated with this framework without custom coding.
34   *
35   * <p>This interface is not intended for application developers. It is available
36   * to handlers who want to develop their own web workflow.
37   *
38   * <p>Note: Implementations can implement the Ordered interface to be able to
39   * specify a sorting order and thus a priority for getting applied by
40   * DispatcherPortlet. Non-Ordered instances get treated as lowest priority.
41   *
42   * @author John A. Lewis
43   * @since 2.0
44   * @see org.springframework.web.portlet.mvc.SimpleControllerHandlerAdapter
45   */
46  public interface HandlerAdapter {
47      
48      /**
49       * Given a handler instance, return whether or not this HandlerAdapter can
50       * support it. Typical HandlerAdapters will base the decision on the handler
51       * type. HandlerAdapters will usually only support one handler type each.
52       * <p>A typical implementation:
53       * <p><code>
54       * return (handler instanceof MyHandler);
55       * </code>
56       * @param handler handler object to check
57       * @return whether or not this object can use the given handler
58       */
59      boolean supports(Object   handler); 
60  
61      /**
62       * Use the given handler to handle this action request.
63       * The workflow that is required may vary widely.
64       * @param request current action request
65       * @param response current action response
66       * @param handler handler to use. This object must have previously been passed
67       * to the <code>supports</code> method of this interface, which must have
68       * returned true.
69       * @throws Exception in case of errors
70       */
71      void handleAction(ActionRequest request, ActionResponse response, Object   handler) throws Exception  ;
72  
73      /**
74       * Use the given handler to handle this render request.
75       * The workflow that is required may vary widely.
76       * @param request current render request
77       * @param response current render response
78       * @param handler handler to use. This object must have previously been passed
79       * to the <code>supports</code> method of this interface, which must have
80       * returned <code>true</code>.
81       * @throws Exception in case of errors
82       * @return ModelAndView object with the name of the view and the required
83       * model data, or <code>null</code> if the request has been handled directly
84       */
85      ModelAndView handleRender(RenderRequest request, RenderResponse response, Object   handler) throws Exception  ;
86  
87  }
88
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