/******************************************************************************
* JBoss, a division of Red Hat *
* Copyright 2006, Red Hat Middleware, LLC, and individual *
* contributors as indicated by the @authors tag. See the *
* copyright.txt in the distribution for a full listing of *
* individual contributors. *
* *
* This is free software; you can redistribute it and/or modify it *
* under the terms of the GNU Lesser General Public License as *
* published by the Free Software Foundation; either version 2.1 of *
* the License, or (at your option) any later version. *
* *
* This software is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this software; if not, write to the Free *
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA *
* 02110-1301 USA, or see the FSF site: http://www.fsf.org. *
******************************************************************************/
package org.jboss.portal.web.command;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* This servlet is used to execute command coming from another context through a dispatching request. The invocation is
* detyped in order to allow redeployment and avoid class cast exception.
*
* @author <a href="mailto:julien@jboss.org">Julien Viet</a>
* @version $Revision: 1.1 $
*/
public class CommandServlet extends HttpServlet
{
/** . */
private static final ThreadLocal localCmd = new ThreadLocal();
/** . */
private static final ThreadLocal localResponse = new ThreadLocal();
/** . */
private static final ThreadLocal localThrowable = new ThreadLocal();
/**
* <p>Execute a command after having performed a request dispatch in the target servlet context.</p>
* <p/>
* <p>The provided callback argument must expose a public non static and non abstract method with the signature
* <code>execute(HttpServletRequest,HttpServletResponse)</code>. This method must return an object and can declare
* any exception. This method will be invoked after the request dispatch operation is done.</p>
* <p/>
* <p>Any throwable thrown by the callback invocation will be wrapped in a <code>ServletException</code> and
* rethrown, unless it is an instance of <code>ServletException</code> or <code>IOException</code>.</p>
*
* @param callback the callback to invoke after the inclusion is done
* @param targetContext the target servlet context
* @throws IOException likely thrown by the request dispatch operation
* @throws ServletException wraps any exception thrown by the callback
*/
public static Object include(
HttpServletRequest request,
HttpServletResponse response,
Object callback,
ServletContext targetContext) throws ServletException, IOException
{
try
{
localCmd.set(callback);
RequestDispatcher switcher = targetContext.getRequestDispatcher("/jbossportlet");
switcher.include(request, response);
//
Throwable throwable = (Throwable)localThrowable.get();
//
if (throwable != null)
{
if (throwable instanceof IOException)
{
throw (IOException)throwable;
}
else if (throwable instanceof ServletException)
{
throw (ServletException)throwable;
}
else
{
ServletException se = new ServletException();
se.initCause(throwable);
throw se;
}
}
//
return localResponse.get();
}
finally
{
localCmd.set(null);
localResponse.set(null);
localThrowable.set(null);
}
}
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
{
Object cmd = localCmd.get();
//
if (cmd != null)
{
try
{
Method methods = cmd.getClass().getMethod(
"execute",
new Class[]{
HttpServletRequest.class,
HttpServletResponse.class});
//
Object response = methods.invoke(cmd, new Object[]{req, resp});
//
localResponse.set(response);
}
catch (NoSuchMethodException e)
{
throw new Error("No execute method found on the command", e);
}
catch (InvocationTargetException e)
{
// Log the wrappee
Throwable wrappee = e.getTargetException();
// Here we wrap it and rethrow
localThrowable.set(wrappee);
}
catch (IllegalAccessException e)
{
throw new Error("Unexpected IllegalAccessException during command invocation", e);
}
}
else
{
// That should not happen
throw new Error("No command found");
}
}
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
{
doGet(req, resp);
}
}