// ========================================================================
   // Copyright (c) 2006-2009 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);
             }
         }
     }
 }