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Spring Framework example source code file (AbstractController.java)
This example Spring Framework source code file (AbstractController.java) is included in the DevDaily.com
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The Spring Framework AbstractController.java source code
/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.portlet.mvc;
import javax.portlet.ActionRequest;
import javax.portlet.ActionResponse;
import javax.portlet.PortletException;
import javax.portlet.PortletSession;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;
import javax.portlet.WindowState;
import org.springframework.web.portlet.ModelAndView;
import org.springframework.web.portlet.handler.PortletContentGenerator;
import org.springframework.web.portlet.util.PortletUtils;
/**
* Convenient superclass for controller implementations, using the Template
* Method design pattern.
*
* <p>As stated in the {@link Controller Controller}
* interface, a lot of functionality is already provided by certain abstract
* base controllers. The AbstractController is one of the most important
* abstract base controller providing basic features such controlling if a
* session is required and render caching.
*
* <p>Workflow
* (<a href="Controller.html#workflow">and that defined by interface):
* <ol>
* <li>If this is an action request, {@link #handleActionRequest handleActionRequest}
* will be called by the DispatcherPortlet once to perform the action defined by this
* controller.</li>
* <li>If a session is required, try to get it (PortletException if not found).
* <li>Call method {@link #handleActionRequestInternal handleActionRequestInternal},
* (optionally synchronizing around the call on the PortletSession),
* which should be overridden by extending classes to provide actual functionality to
* perform the desired action of the controller. This will be executed only once.</li>
* <li>For a straight render request, or the render phase of an action request (assuming the
* same controller is called for the render phase -- see tip below),
* {@link #handleRenderRequest handleRenderRequest} will be called by the DispatcherPortlet
* repeatedly to render the display defined by this controller.</li>
* <li>If a session is required, try to get it (PortletException if none found).
* <li>It will control caching as defined by the cacheSeconds property.
* <li>Call method {@link #handleRenderRequestInternal handleRenderRequestInternal},
* (optionally synchronizing around the call on the PortletSession),
* which should be overridden by extending classes to provide actual functionality to
* return {@link org.springframework.web.portlet.ModelAndView ModelAndView} objects.
* This will be executed repeatedly as the portal updates the current displayed page.</li>
* </ol>
*
* <p>Exposed configuration properties
* (<a href="Controller.html#config">and those defined by interface):
* <table border="1">
* <tr>
* <td>name
* <td>default |
* <td>description
* </tr>
* <tr>
* <td>requiresSession
* <td>false
* <td>whether a session should be required for requests to be able to
* be handled by this controller. This ensures, derived controller
* can - without fear of Nullpointers - call request.getSession() to
* retrieve a session. If no session can be found while processing
* the request, a PortletException will be thrown</td>
* </tr>
* <tr>
* <td>synchronizeOnSession
* <td>false
* <td>whether the calls to handleRenderRequestInternal and
* <code>handleRenderRequestInternal should be
* synchronized around the PortletSession, to serialize invocations
* from the same client. No effect if there is no PortletSession.
* </td>
* </tr>
* <tr>
* <td>cacheSeconds
* <td>-1
* <td>indicates the amount of seconds to specify caching is allowed in
* the render response generatedby this request. 0 (zero) will indicate
* no caching is allowed at all, -1 (the default) will not override the
* portlet configuration and any positive number will cause the render
* response to declare the amount indicated as seconds to cache the content</td>
* </tr>
* <tr>
* <td>renderWhenMinimized
* <td>false
* <td>whether should be rendered when the portlet is in a minimized state --
* will return null for the ModelandView when the portlet is minimized
* and this is false</td>
* </tr>
* </table>
*
* <p>TIP: The controller mapping will be run twice by the PortletDispatcher for
* action requests -- once for the action phase and again for the render phase. You can
* reach the render phase of a different controller by simply changing the values for the
* criteria your mapping is using, such as portlet mode or a request parameter, during the
* action phase of your controller. This is very handy since redirects within the portlet
* are apparently impossible. Before doing this, it is usually wise to call
* <code>clearAllRenderParameters and then explicitly set all the parameters that
* you want the new controller to see. This avoids unexpected parameters from being passed
* to the render phase of the second controller, such as the parameter indicating a form
* submit ocurred in an <code>AbstractFormController.
*
* <p>Thanks to Rainer Schmitz and Nick Lothian for their suggestions!
*
* @author John A. Lewis
* @author Juergen Hoeller
* @since 2.0
*/
public abstract class AbstractController extends PortletContentGenerator implements Controller {
private boolean synchronizeOnSession = false;
private boolean renderWhenMinimized = false;
/**
* Set if controller execution should be synchronized on the session,
* to serialize parallel invocations from the same client.
* <p>More specifically, the execution of the handleActionRequestInternal
* method will get synchronized if this flag is "true". The best available
* session mutex will be used for the synchronization; ideally, this will
* be a mutex exposed by HttpSessionMutexListener.
* <p>The session mutex is guaranteed to be the same object during
* the entire lifetime of the session, available under the key defined
* by the <code>SESSION_MUTEX_ATTRIBUTE constant. It serves as a
* safe reference to synchronize on for locking on the current session.
* <p>In many cases, the PortletSession reference itself is a safe mutex
* as well, since it will always be the same object reference for the
* same active logical session. However, this is not guaranteed across
* different servlet containers; the only 100% safe way is a session mutex.
* @see #handleActionRequestInternal
* @see org.springframework.web.util.HttpSessionMutexListener
* @see org.springframework.web.portlet.util.PortletUtils#getSessionMutex(javax.portlet.PortletSession)
*/
public final void setSynchronizeOnSession(boolean synchronizeOnSession) {
this.synchronizeOnSession = synchronizeOnSession;
}
/**
* Return whether controller execution should be synchronized on the session.
*/
public final boolean isSynchronizeOnSession() {
return this.synchronizeOnSession;
}
/**
* Set if the controller should render an view when the portlet is in
* a minimized window. The default is false.
* @see javax.portlet.RenderRequest#getWindowState
* @see javax.portlet.WindowState#MINIMIZED
*/
public final void setRenderWhenMinimized(boolean renderWhenMinimized) {
this.renderWhenMinimized = renderWhenMinimized;
}
/**
* Return whether controller will render when portlet is minimized.
*/
public final boolean isRenderWhenMinimized() {
return this.renderWhenMinimized;
}
public void handleActionRequest(ActionRequest request, ActionResponse response) throws Exception {
// Delegate to PortletContentGenerator for checking and preparing.
check(request, response);
// Execute in synchronized block if required.
if (this.synchronizeOnSession) {
PortletSession session = request.getPortletSession(false);
if (session != null) {
synchronized (session) {
handleActionRequestInternal(request, response);
return;
}
}
}
handleActionRequestInternal(request, response);
}
public ModelAndView handleRenderRequest(RenderRequest request, RenderResponse response) throws Exception {
// If the portlet is minimized and we don't want to render then return null.
if (WindowState.MINIMIZED.equals(request.getWindowState()) && !this.renderWhenMinimized) {
return null;
}
// Delegate to PortletContentGenerator for checking and preparing.
checkAndPrepare(request, response);
// Execute in synchronized block if required.
if (this.synchronizeOnSession) {
PortletSession session = request.getPortletSession(false);
if (session != null) {
Object mutex = PortletUtils.getSessionMutex(session);
synchronized (mutex) {
return handleRenderRequestInternal(request, response);
}
}
}
return handleRenderRequestInternal(request, response);
}
/**
* Subclasses are meant to override this method if the controller
* is expected to handle action requests. The contract is the same as
* for <code>handleActionRequest.
* <p>The default implementation throws a PortletException.
* @see #handleActionRequest
* @see #handleRenderRequestInternal
*/
protected void handleActionRequestInternal(ActionRequest request, ActionResponse response)
throws Exception {
throw new PortletException("[" + getClass().getName() + "] does not handle action requests");
}
/**
* Subclasses are meant to override this method if the controller
* is expected to handle render requests. The contract is the same as
* for <code>handleRenderRequest.
* <p>The default implementation throws a PortletException.
* @see #handleRenderRequest
* @see #handleActionRequestInternal
*/
protected ModelAndView handleRenderRequestInternal(RenderRequest request, RenderResponse response)
throws Exception {
throw new PortletException("[" + getClass().getName() + "] does not handle render requests");
}
}
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