AbstractCommandController


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.mvc;
18  
19  import javax.portlet.ActionRequest;
20  import javax.portlet.ActionResponse;
21  import javax.portlet.RenderRequest;
22  import javax.portlet.RenderResponse;
23  
24  import org.springframework.validation.BindException;
25  import org.springframework.web.portlet.ModelAndView;
26  import org.springframework.web.portlet.bind.PortletRequestDataBinder;
27  
28  /**
29   * <p>Abstract base class for custom command controllers. Autopopulates a
30   * command bean from the request. For command validation, a validator
31   * (property inherited from BaseCommandController) can be used.</p>
32   *
33   * <p>This command controller should preferrable not be used to handle form
34   * submission, because functionality for forms is more offered in more
35   * detail by the {@link org.springframework.web.portlet.mvc.AbstractFormController
36   * AbstractFormController} and its corresponding implementations.</p>
37   *
38   * <p><b><a name="config">Exposed configuration properties</a>
39   * (<a HREF="BaseCommandController.html#config">and those defined by superclass</a>):</b><br>
40   * <i>none</i> (so only those available in superclass).</p>
41   *
42   * <p><b><a name="workflow">Workflow
43   * (<a name="BaseCommandController.html#workflow">and that defined by superclass</a>):</b><br>
44   *
45   * @author John A. Lewis
46   * @author Juergen Hoeller
47   * @since 2.0
48   * @see #setCommandClass
49   * @see #setCommandName
50   * @see #setValidator
51   */
52  public abstract class AbstractCommandController extends BaseCommandController {
53  
54      /**
55       * This render parameter is used to indicate forward to the render phase
56       * that a valid command (and errors) object is in the session.
57       */
58      private static final String   COMMAND_IN_SESSION_PARAMETER = "command-in-session";
59  
60      private static final String   TRUE = Boolean.TRUE.toString();
61  
62  
63      /**
64       * Create a new AbstractCommandController.
65       */
66      public AbstractCommandController() {
67      }
68  
69      /**
70       * Create a new AbstractCommandController.
71       * @param commandClass class of the command bean
72       */
73      public AbstractCommandController(Class   commandClass) {
74          setCommandClass(commandClass);
75      }
76  
77      /**
78       * Create a new AbstractCommandController.
79       * @param commandClass class of the command bean
80       * @param commandName name of the command bean
81       */
82      public AbstractCommandController(Class   commandClass, String   commandName) {
83          setCommandClass(commandClass);
84          setCommandName(commandName);
85      }
86  
87  
88      protected final void handleActionRequestInternal(ActionRequest request, ActionResponse response)
89              throws Exception   {
90  
91          // Create the command object.
92          Object   command = getCommand(request);
93  
94          // Compute the errors object.
95          PortletRequestDataBinder binder = bindAndValidate(request, command);
96          BindException errors = new BindException(binder.getBindingResult());
97  
98          // Actually handle the action.
99          handleAction(request, response, command, errors);
100 
101         // Pass the command and errors forward to the render phase.
102         setRenderCommandAndErrors(request, command, errors);
103         setCommandInSession(response);
104     }
105 
106     protected final ModelAndView handleRenderRequestInternal(
107             RenderRequest request, RenderResponse response) throws Exception   {
108 
109         Object   command = null;
110         BindException errors = null;
111 
112         // get the command and errors objects from the session, if they exist
113         if (isCommandInSession(request)) {
114             logger.debug("Render phase obtaining command and errors objects from session");
115             command = getRenderCommand(request);
116             errors = getRenderErrors(request);
117         }
118         else {
119             logger.debug("Render phase creating new command and errors objects");
120         }
121 
122         // If no command object was in the session, create a new one.
123         if (command == null) {
124             command = getCommand(request);
125         }
126 
127         // If no errors object was in the session, compute a new one.
128         if (errors == null) {
129             PortletRequestDataBinder binder = bindAndValidate(request, command);
130             errors = new BindException(binder.getBindingResult());
131         }
132 
133         return handleRender(request, response, command, errors);
134     }
135 
136 
137     /**
138      * Template method for request handling, providing a populated and validated instance
139      * of the command class, and an Errors object containing binding and validation errors.
140      * <p>Call <code>errors.getModel()</code> to populate the ModelAndView model
141      * with the command and the Errors instance, under the specified command name,
142      * as expected by the "spring:bind" tag.
143      * @param request current action request
144      * @param response current action response
145      * @param command the populated command object
146      * @param errors validation errors holder
147      * @see org.springframework.validation.Errors
148      * @see org.springframework.validation.BindException#getModel
149      */
150     protected abstract void handleAction(
151             ActionRequest request, ActionResponse response, Object   command, BindException errors)
152             throws Exception  ;
153 
154     /**
155      * Template method for render request handling, providing a populated and validated instance
156      * of the command class, and an Errors object containing binding and validation errors.
157      * <p>Call <code>errors.getModel()</code> to populate the ModelAndView model
158      * with the command and the Errors instance, under the specified command name,
159      * as expected by the "spring:bind" tag.
160      * @param request current render request
161      * @param response current render response
162      * @param command the populated command object
163      * @param errors validation errors holder
164      * @return a ModelAndView to render, or null if handled directly
165      * @see org.springframework.validation.Errors
166      * @see org.springframework.validation.BindException#getModel
167      */
168     protected abstract ModelAndView handleRender(
169             RenderRequest request, RenderResponse response, Object   command, BindException errors)
170             throws Exception  ;
171 
172 
173     /**
174      * Return the name of the render parameter that indicates there
175      * is a valid command (and errors) object in the session.
176      * @return the name of the render parameter
177      * @see javax.portlet.RenderRequest#getParameter
178      */
179     protected String   getCommandInSessionParameterName() {
180         return COMMAND_IN_SESSION_PARAMETER;
181     }
182 
183     /**
184      * Set the action response parameter that indicates there is a
185      * command (and errors) object in the session for the render phase.
186      * @param response the current action response
187      * @see #getCommandInSessionParameterName
188      * @see #isCommandInSession
189      */
190     protected final void setCommandInSession(ActionResponse response) {
191         if (logger.isDebugEnabled()) {
192             logger.debug("Setting render parameter [" + getCommandInSessionParameterName() +
193                     "] to indicate a valid command (and errors) object are in the session");
194         }
195         try {
196             response.setRenderParameter(getCommandInSessionParameterName(), TRUE);
197         }
198         catch (IllegalStateException   ex) {
199             // Ignore in case sendRedirect was already set.
200         }
201     }
202 
203     /**
204      * Determine if there is a valid command (and errors) object in the
205      * session for this render request.
206      * @param request current render request
207      * @return if there is a valid command object in the session
208      * @see #getCommandInSessionParameterName
209      * @see #setCommandInSession
210      */
211     protected final boolean isCommandInSession(RenderRequest request) {
212         return TRUE.equals(request.getParameter(getCommandInSessionParameterName()));
213     }
214 
215 }
216
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