jspdispatcherservlet.java

一个java写的business process management系统

/*
 * Copyright (c) 2003-2004, Alexander Greif
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the Flow4J-Eclipse project nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 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.
 */

package net.orthanc.flow4j.runtime.web.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.orthanc.flow4j.runtime.Flow4JRuntimeConsts;
import net.orthanc.flow4j.runtime.web.WebFlowDictionary;

/**
 * Class JSPDispatcherServlet first executes the flow that weas specified in the 
 * ULI path info, and then dispatches the request to the resource that is returned by a 
 * template flowlet at the end of the flow.
 * The resource can be dynamic, or static. 
 * @author agreif
 * 
 */
public class JSPDispatcherServlet extends FlowDispatcherServlet {

	/**
	 * Executes the flow in the superclass and then
	 * the request is dispatched to the resource that is returned by a 
	 * template flowlet at the end of the flow.
	 * The resource can be dynamic, or static. 
	 * @see net.orthanc.flow4j.runtime.web.servlet.FlowDispatcherServlet#postFlowExecution(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, net.orthanc.flow4j.runtime.web.WebFlowDictionary)
	 */
	protected void postFlowExecution(
		HttpServletRequest req,
		HttpServletResponse res,
		WebFlowDictionary dictionary) throws Flow4JServletException {
		// TODO Auto-generated method stub
		super.postFlowExecution(req, res, dictionary);

		//	determine template name
		String templateName =
			(String) dictionary.get(Flow4JRuntimeConsts.DICT_KEY_TEMPLATE_NAME);
		if (templateName == null)
			throw new Flow4JServletException("No template specified");

		//	forward request
		StringBuffer forwardPath = new StringBuffer();
		if (!templateName.startsWith("/"))
			forwardPath.append("/");

		forwardPath.append(templateName);

		try {
			forward(req, res, forwardPath.toString());
		} catch (Exception e) {
			throw new Flow4JServletException("could not forward request to: " + forwardPath, e);
		}
	}




	/**
	 * Forwards the request to the given resource.
	 */
	private void forward(
		HttpServletRequest req,
		HttpServletResponse res,
		String forwardPath)
		throws IOException, ServletException {

		// Create a RequestDispatcher the corresponding resource
		RequestDispatcher rd =
			getServletContext().getRequestDispatcher(forwardPath);
		if (rd == null)
			throw new Flow4JServletException(
				"Cannot forward to: " + forwardPath);

		// Forward control to the specified resource
		rd.forward(req, res);
	}




}