| // |
| // ======================================================================== |
| // Copyright (c) 1995-2016 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 |
| { |
| /** |
| * Produce output that lists all of the request parameters |
| */ |
| public static class ParamHandler extends AbstractHandler |
| { |
| public void handle( String target, |
| Request baseRequest, |
| HttpServletRequest request, |
| HttpServletResponse response ) throws IOException, |
| ServletException |
| { |
| Map<String, String[]> params = request.getParameterMap(); |
| if (params.size() > 0) |
| { |
| response.setContentType("text/plain"); |
| response.getWriter().println(JSON.toString(params)); |
| baseRequest.setHandled(true); |
| } |
| } |
| } |
| |
| /** |
| * Add a request attribute, but produce no output. |
| */ |
| public static class WelcomeWrapHandler extends 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); |
| } |
| } |
| |
| public static void main( String[] args ) throws Exception |
| { |
| Server server = new Server(8080); |
| |
| // create the handlers |
| Handler param = new ParamHandler(); |
| HandlerWrapper wrapper = new WelcomeWrapHandler(); |
| Handler hello = new HelloHandler(); |
| Handler dft = new DefaultHandler(); |
| RequestLogHandler requestLog = new RequestLogHandler(); |
| |
| // configure request logging |
| File requestLogFile = File.createTempFile("demo", "log"); |
| NCSARequestLog ncsaLog = new NCSARequestLog( |
| requestLogFile.getAbsolutePath()); |
| requestLog.setRequestLog(ncsaLog); |
| |
| // 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, requestLog }); |
| |
| // Handler tree looks like the following |
| // <pre> |
| // Server |
| // + HandlerCollection |
| // . + HandlerList |
| // . | + param (ParamHandler) |
| // . | + wrapper (WelcomeWrapHandler) |
| // . | | \ hello (HelloHandler) |
| // . | \ dft (DefaultHandler) |
| // . \ requestLog (RequestLogHandler) |
| // </pre> |
| |
| server.setHandler(handlers); |
| |
| server.start(); |
| server.join(); |
| } |
| } |