craigmcc 2003/10/09 20:55:51
Added: chain/src/java/org/apache/commons/chain/web/servlet
ChainProcessor.java
Log:
Add a simple servlet that lets you dispatch incoming requests to an
appropriate chain. Three sample mapping commands (by path info,
extension matching, or a named request parameter) were checked in earlier.
Revision Changes Path
1.1
jakarta-commons-sandbox/chain/src/java/org/apache/commons/chain/web/servlet/ChainProcessor.java
Index: ChainProcessor.java
===================================================================
/*
* $Header:
/home/cvs/jakarta-commons-sandbox/chain/src/java/org/apache/commons/chain/web/servlet/ChainProcessor.java,v
1.1 2003/10/10 03:55:51 craigmcc Exp $
* $Revision: 1.1 $
* $Date: 2003/10/10 03:55:51 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2003 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 acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [EMAIL PROTECTED]
*
* 5. Products derived from this software may not be called "Apache"
* nor may "Apache" appear in their names without prior written
* permission of the Apache Group.
*
* 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
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS 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.
* ====================================================================
*
* 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 org.apache.commons.chain.web.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.chain.Catalog;
import org.apache.commons.chain.Command;
import org.apache.commons.chain.Context;
import org.apache.commons.chain.web.ChainServlet;
/**
* <p>Custom subclass of [EMAIL PROTECTED] ChainServlet} that also dispatches
incoming
* requests to a configurable [EMAIL PROTECTED] Command} loaded from the configured
* [EMAIL PROTECTED] Catalog}.</p>
*
* <p>In addition to the <em>servlet</em> init parameters supported by
* [EMAIL PROTECTED] ChainServlet}, this class supports the following additional
* parameters:</p>
* <ul>
* <li><strong>org.apache.commons.chain.COMMAND</strong> - Name of the
* [EMAIL PROTECTED] Command} (looked up in our configured [EMAIL PROTECTED]
Catalog} used
* to process all incoming servlet requests. If not specified,
* defaults to <code>command</code>.</li>
* </ul>
*
* <p>Also, the <code>org.apache.commons.chain.CONFIG_ATTR</code>
* init parameter is also used to identify the [EMAIL PROTECTED] Context} attribute
under
* which our configured [EMAIL PROTECTED] Catalog} will be made available to
* [EMAIL PROTECTED] Command}s processing our requests, in addition to its definition
* of the <code>ServletContext</code> attribute key under which the
* [EMAIL PROTECTED] Catalog} is available.</p>
*/
public class ChainProcessor extends ChainServlet {
// ------------------------------------------------------ Manifest Constants
/**
* <p>The name of the servlet init parameter containing the name of the
* [EMAIL PROTECTED] Command} (loaded from our configured [EMAIL PROTECTED]
Catalog} to use
* for processing each incoming request.</p>
*/
public static final String COMMAND =
"org.apache.commons.chain.COMMAND";
/**
* <p>The default command name.</p>
*/
private static final String COMMAND_DEFAULT = "command";
// ------------------------------------------------------ Instance Variables
/**
* <p>The name of the context attribute under which our [EMAIL PROTECTED]
Catalog}
* is stored. This value is also used as the name of the
* context attribute under which the catalog is exposed to commands.</p>
*/
private String attribute = null;
/**
* <p>The name of the [EMAIL PROTECTED] Command} to be executed for each incoming
* request.</p>
*/
private String command = null;
// --------------------------------------------------------- Servlet Methods
/**
* <p>Cache the name of the command we should execute for each request.</p>
*
* @exception ServletException if an initialization error occurs
*/
public void init() throws ServletException {
super.init();
attribute = getServletConfig().getInitParameter(CONFIG_ATTR);
if (attribute == null) {
attribute = CONFIG_ATTR_DEFAULT;
}
command = getServletConfig().getInitParameter(COMMAND);
if (command == null) {
command = COMMAND_DEFAULT;
}
}
/**
* <p>Configure a [EMAIL PROTECTED] ServletWebContext} for the current request,
and
* pass it to the <code>execute()</code> method of the specified
* [EMAIL PROTECTED] Command}, loaded from our configured [EMAIL PROTECTED]
Catalog}.</p>
*
* @param request The request we are processing
* @param response The response we are creating
*
* @exception IOException if an input/output error occurs
* @exception ServletException if a servlet exception occurs
*/
public void service(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
ServletWebContext context =
new ServletWebContext(getServletContext(), request, response);
Catalog catalog =
(Catalog) getServletContext().getAttribute(this.attribute);
context.put(this.attribute, catalog);
Command command = catalog.getCommand(this.command);
try {
command.execute(context);
} catch (Exception e) {
throw new ServletException(e);
}
}
}
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