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//
// ========================================================================
// Copyright (c) 1995-2012 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.embedded;
import java.io.File;
import java.io.IOException;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.NCSARequestLog;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.AbstractHandler;
import org.eclipse.jetty.server.handler.DefaultHandler;
import org.eclipse.jetty.server.handler.HandlerCollection;
import org.eclipse.jetty.server.handler.HandlerList;
import org.eclipse.jetty.server.handler.HandlerWrapper;
import org.eclipse.jetty.server.handler.RequestLogHandler;
import org.eclipse.jetty.util.ajax.JSON;
/* ------------------------------------------------------------ */
/**
* Frequently many handlers are combined together to handle different aspects of
* a request. A handler may:
* <ul>
* <li>handle the request and completely generate the response
* <li>partially handle the request, but defer response generation to another
* handler.
* <li>select another handler to pass the request to.
* <li>use business logic to decide to do one of the above.
* </ul>
*
* Multiple handlers may be combined with:
* <ul>
* <li>{@link HandlerWrapper} which will nest one handler inside another. In
* this example, the HelloHandler is nested inside a HandlerWrapper that sets
* the greeting as a request attribute.
* <li>{@link HandlerList} which will call a collection of handlers until the
* request is marked as handled. In this example, a list is used to combine the
* param handler (which only handles the request if there are parameters) and
* the wrapper handler. Frequently handler lists are terminated with the
* {@link DefaultHandler}, which will generate a suitable 404 response if the
* request has not been handled.
* <li>{@link HandlerCollection} which will call each handler regardless if the
* request has been handled or not. Typically this is used to always pass a
* request to the logging handler.
* </ul>
*/
public class ManyHandlers
{
public static void main(String[] args) throws Exception
{
Server server = new Server(8080);
// create the handlers
Handler param = new ParamHandler();
HandlerWrapper wrapper = new HandlerWrapper()
{
@Override
public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException,
ServletException
{
request.setAttribute("welcome","Hello");
super.handle(target,baseRequest,request,response);
}
};
Handler hello = new HelloHandler();
Handler dft = new DefaultHandler();
RequestLogHandler log = new RequestLogHandler();
// configure logs
log.setRequestLog(new NCSARequestLog(File.createTempFile("demo","log").getAbsolutePath()));
// create the handler collections
HandlerCollection handlers = new HandlerCollection();
HandlerList list = new HandlerList();
// link them all together
wrapper.setHandler(hello);
list.setHandlers(new Handler[]
{ param, wrapper, dft });
handlers.setHandlers(new Handler[]
{ list, log });
server.setHandler(handlers);
server.start();
server.join();
}
public static class ParamHandler extends AbstractHandler
{
public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
{
Map params = request.getParameterMap();
if (params.size() > 0)
{
response.setContentType("text/plain");
response.getWriter().println(JSON.toString(params));
((Request)request).setHandled(true);
}
}
}
}
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