framework/src/net/sf/tapestry/callback/PageCallback.java

/*
 *  ====================================================================
 *  The Apache Software License, Version 1.1
 *
 *  Copyright (c) 2002 The Apache Software Foundation.  All rights
 *  reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution,
 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Apache Software Foundation (http://www.apache.org/)."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Apache" and "Apache Software Foundation" and
 *  "Apache Tapestry" must not be used to endorse or promote products
 *  derived from this software without prior written permission. For
 *  written permission, please contact apache@apache.org.
 *
 *  5. Products derived from this software may not be called "Apache",
 *  "Apache Tapestry", nor may "Apache" appear in their name, without
 *  prior written permission of the Apache Software Foundation.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of the Apache Software Foundation.  For more
 *  information on the Apache Software Foundation, please see
 *  <http://www.apache.org/>.
 */
package net.sf.tapestry.callback;

import net.sf.tapestry.IPage;
import net.sf.tapestry.IRequestCycle;
import net.sf.tapestry.RequestCycleException;

/**
 *  Simple callback for returning to a page.
 *  <p>
 *  Example usage of <tt>PageCallback</tt>:
 *  <p>
 *  The Home page ensure a user is 
 *  authenticated in the {@link net.sf.tapestry.IPage#validate(IRequestCycle)} 
 *  method.  If the user is not authenticated, they are redirected to the Login 
 *  page, after setting a callback in the Login page.
 *  <p>
 *  The Login page <tt>formSubmit()</tt> {@link net.sf.tapestry.IActionListener} 
 *  authenticates the user and then invokes {@link ICallback#performCallback(IRequestCycle)} 
 *  to the Home page.
 *  <pre>
 *  public class Home extends BasePage {
 * 
 *      public void validate(IRequestCycle cycle) throws RequestCycleException {            
 *          Visit visit = (Visit) getVisit();
 *      
 *          if (!visit.isAuthenticated()) {
 *              Login login = (Login) cycle.getPage("Login");
 *
 *              login.setCallback(new PageCallback(this));
 *              
 *              throw new PageRedirectException(login);
 *          }            
 *      }
 *  }
 *
 *  public Login extends BasePage {
 * 
 *      private ICallback _callback;
 *
 *      public void setCallback(ICallback _callback) {
 *          _callback = callback;
 *      }
 *
 *      public void formSubmit(IRequestCycle cycle) throws RequestCycleException {
 *          // Authentication code
 *          ..
 *   
 *          Visit visit = (Visit) getVisit();
 *
 *          visit.setAuthenticated(true);
 *  
 *          if (_callback != null) {
 *              _callback.performCallback(cycle);
 *          }
 *      }
 *  }    
 *  </pre>
 *
 *  @version $Id$
 *  @author Howard Lewis Ship
 *  @since 0.2.9
 *
 **/

public class PageCallback implements ICallback
{
    /**
     *  @since 2.0.4
     * 
     **/

    private static final long serialVersionUID = -3286806776105690068L;

    private String _pageName;

    public PageCallback(String pageName)
    {
        _pageName = pageName;
    }

    public PageCallback(IPage page)
    {
        this(page.getName());
    }

    public String toString()
    {
        return "PageCallback[" + _pageName + "]";
    }

    /**
     *  Invokes {@link IRequestCycle#setPage(String)} to select the previously
     *  identified page as the response page.
     *
     **/

    public void performCallback(IRequestCycle cycle) throws RequestCycleException
    {
        cycle.setPage(_pageName);
    }
}