Java tutorial
/** * Copyright (c) 2014 openHAB UG (haftungsbeschraenkt) and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html */ package org.eclipse.smarthome.ui.internal.proxy; import java.io.IOException; import java.net.URI; import java.util.Hashtable; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.httpclient.Credentials; import org.apache.commons.httpclient.Header; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.UsernamePasswordCredentials; import org.apache.commons.httpclient.auth.AuthScope; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.io.IOUtils; import org.eclipse.smarthome.model.core.ModelRepository; import org.eclipse.smarthome.model.sitemap.Image; import org.eclipse.smarthome.model.sitemap.Sitemap; import org.eclipse.smarthome.model.sitemap.Video; import org.eclipse.smarthome.model.sitemap.Widget; import org.eclipse.smarthome.ui.items.ItemUIRegistry; import org.osgi.service.http.HttpContext; import org.osgi.service.http.HttpService; import org.osgi.service.http.NamespaceException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * The proxy servlet is used by image and video widgets. As its name suggests, it proxies the content, so * that it is possible to include resources (images/videos) from the LAN in the openHAB UI. This is * especially useful for webcams as you would not want to make them directly available to the internet. * * The servlet registers as "/proxy" and expects the two parameters "sitemap" and "widgetId". It will * hence provide the data of the url specified in the according widget. Note that it does NOT allow * general access to any servers in the LAN - only urls that are specified in a sitemap are accessible. * * It is also possible to use credentials in a url, e.g. "http://user:pwd@localserver/image.jpg" - * the proxy servlet will be able to access the content and provide it to the openHAB UIs through the * standard openHAB authentication mechanism (if enabled). * * This servlet also supports data streams, such as a webcam video stream etc. * * @author Kai Kreuzer - Initial contribution and API */ public class ProxyServlet extends HttpServlet { /** the alias for this servlet */ public static final String PROXY_ALIAS = "proxy"; private static final Logger logger = LoggerFactory.getLogger(ProxyServlet.class); private static final long serialVersionUID = -4716754591953017793L; protected HttpService httpService; protected ItemUIRegistry itemUIRegistry; protected ModelRepository modelRepository; protected void setItemUIRegistry(ItemUIRegistry itemUIRegistry) { this.itemUIRegistry = itemUIRegistry; } protected void unsetItemUIRegistry(ItemUIRegistry itemUIRegistry) { this.itemUIRegistry = null; } protected void setModelRepository(ModelRepository modelRepository) { this.modelRepository = modelRepository; } protected void unsetModelRepository(ModelRepository modelRepository) { this.modelRepository = null; } protected void setHttpService(HttpService httpService) { this.httpService = httpService; } protected void unsetHttpService(HttpService httpService) { this.httpService = null; } protected void activate() { try { logger.debug("Starting up proxy servlet at /" + PROXY_ALIAS); Hashtable<String, String> props = new Hashtable<String, String>(); httpService.registerServlet("/" + PROXY_ALIAS, this, props, createHttpContext()); } catch (NamespaceException e) { logger.error("Error during servlet startup: {}", e.getMessage()); } catch (ServletException e) { logger.error("Error during servlet startup: {}", e.getMessage()); } } protected void deactivate() { httpService.unregister("/" + PROXY_ALIAS); } /** * Creates a {@link HttpContext} * @return a {@link HttpContext} */ protected HttpContext createHttpContext() { HttpContext defaultHttpContext = httpService.createDefaultHttpContext(); return defaultHttpContext; } @Override public String getServletInfo() { return "Image and Video Widget Proxy"; } @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String sitemapName = request.getParameter("sitemap"); String widgetId = request.getParameter("widgetId"); if (sitemapName == null) { throw new ServletException("Parameter 'sitemap' must be provided!"); } if (widgetId == null) { throw new ServletException("Parameter 'widget' must be provided!"); } String uriString = null; Sitemap sitemap = (Sitemap) modelRepository.getModel(sitemapName); if (sitemap != null) { Widget widget = itemUIRegistry.getWidget(sitemap, widgetId); if (widget instanceof Image) { Image image = (Image) widget; uriString = image.getUrl(); } else if (widget instanceof Video) { Video video = (Video) widget; uriString = video.getUrl(); } else { if (widget == null) { throw new ServletException("Widget '" + widgetId + "' could not be found!"); } else { throw new ServletException( "Widget type '" + widget.getClass().getName() + "' is not supported!"); } } } else { throw new ServletException("Sitemap '" + sitemapName + "' could not be found!"); } HttpClient httpClient = new HttpClient(); try { // check if the uri uses credentials and configure the http client accordingly URI uri = URI.create(uriString); if (uri.getUserInfo() != null) { String[] userInfo = uri.getUserInfo().split(":"); httpClient.getParams().setAuthenticationPreemptive(true); Credentials creds = new UsernamePasswordCredentials(userInfo[0], userInfo[1]); httpClient.getState() .setCredentials(new AuthScope(uri.getHost(), uri.getPort(), AuthScope.ANY_REALM), creds); } } catch (IllegalArgumentException e) { throw new ServletException("URI '" + uriString + "' is not valid: " + e.getMessage()); } // do the client request GetMethod method = new GetMethod(uriString); httpClient.executeMethod(method); // copy all headers for (Header header : method.getResponseHeaders()) { response.setHeader(header.getName(), header.getValue()); } // now copy/stream the body content IOUtils.copy(method.getResponseBodyAsStream(), response.getOutputStream()); method.releaseConnection(); } }