Java tutorial
/** * Copyright 2015 IBM Corp. All Rights Reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.ibm.watson.ta.retail; import java.io.IOException; import java.net.URI; import java.util.Collections; import java.util.Date; import java.util.List; import java.util.logging.Level; import java.util.logging.Logger; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.annotation.MultipartConfig; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.http.HttpHost; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.CookieStore; import org.apache.http.client.fluent.Executor; import org.apache.http.client.fluent.Request; import org.apache.http.client.fluent.Response; import org.apache.http.cookie.Cookie; import org.apache.http.entity.ContentType; import org.apache.http.entity.InputStreamEntity; import org.apache.http.util.EntityUtils; import com.ibm.json.java.JSONArray; import com.ibm.json.java.JSONObject; @MultipartConfig public class DemoServlet extends HttpServlet { private static Logger logger = Logger.getLogger(DemoServlet.class.getName()); private static final long serialVersionUID = 1L; private String serviceName = "tradeoff_analytics"; // If running locally complete the variables below with the information in VCAP_SERVICES private String baseURL = "https://gateway.watsonplatform.net/tradeoff-analytics/api/"; private String username = "<username>"; private String password = "<password>"; /** * Forward the request to the index.jsp file * * @param req * the Http Servlet request * @param resp * the Http Servlet response * @throws ServletException * the servlet exception * @throws IOException * Signals that an I/O exception has occurred. */ @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.getRequestDispatcher("/index.jsp").forward(req, resp); } /** * Create and POST a request to the Watson service * * @param req * the Http Servlet request * @param resp * the Http Servlet response * @throws ServletException * the servlet exception * @throws IOException * Signals that an I/O exception has occurred. */ @Override protected void doPost(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("UTF-8"); try { String queryStr = req.getQueryString(); String url = baseURL + "/v1/dilemmas"; if (queryStr != null) { url += "?" + queryStr; } URI uri = new URI(url).normalize(); logger.info("posting to " + url); Request newReq = Request.Post(uri); newReq.addHeader("Accept", "application/json"); InputStreamEntity entity = new InputStreamEntity(req.getInputStream()); newReq.bodyString(EntityUtils.toString(entity, "UTF-8"), ContentType.APPLICATION_JSON); Executor executor = this.buildExecutor(uri); Response response = executor.execute(newReq); HttpResponse httpResponse = response.returnResponse(); resp.setStatus(httpResponse.getStatusLine().getStatusCode()); ServletOutputStream servletOutputStream = resp.getOutputStream(); httpResponse.getEntity().writeTo(servletOutputStream); servletOutputStream.flush(); servletOutputStream.close(); logger.info("post done"); } catch (Exception e) { // Log something and return an error message logger.log(Level.SEVERE, "got error: " + e.getMessage(), e); resp.setStatus(HttpStatus.SC_BAD_GATEWAY); } } /** * Gets the <b>VCAP_SERVICES</b> environment variable and return it as a * JSONObject. * * @return the VCAP_SERVICES as Json */ private JSONObject getVcapServices() { String envServices = System.getenv("VCAP_SERVICES"); if (envServices == null) return null; JSONObject sysEnv = null; try { sysEnv = JSONObject.parse(envServices); } catch (IOException e) { // Do nothing, fall through to defaults logger.log(Level.SEVERE, "Error parsing VCAP_SERVICES: " + e.getMessage(), e); } return sysEnv; } @Override public void init() throws ServletException { super.init(); processVCAP_Services(); } /** * If exists, process the VCAP_SERVICES environment variable in order to get * the username, password and baseURL */ private void processVCAP_Services() { logger.info("Processing VCAP_SERVICES"); JSONObject sysEnv = getVcapServices(); if (sysEnv == null) return; logger.info("Looking for: " + serviceName); for (Object key : sysEnv.keySet()) { String keyString = (String) key; logger.info("found key: " + key); if (keyString.startsWith(serviceName)) { JSONArray services = (JSONArray) sysEnv.get(key); JSONObject service = (JSONObject) services.get(0); JSONObject credentials = (JSONObject) service.get("credentials"); baseURL = (String) credentials.get("url"); username = (String) credentials.get("username"); password = (String) credentials.get("password"); logger.info("baseURL = " + baseURL); logger.info("username = " + username); logger.info("password = " + password); } else { logger.info("Doesn't match /^" + serviceName + "/"); } } } /** * Build an executor for the specified url. This disables cookies and sets * preemptive authentication (creds are sent without waiting for a 401). * * NOTE: This is required to avoid issues with load balancers that use * cookies due to Apache Http Client issue: * https://issues.apache.org/jira/browse/HTTPCLIENT-1451 * * @param url * @return */ private Executor buildExecutor(URI url) { return Executor.newInstance().auth(username, password) .authPreemptive(new HttpHost(url.getHost(), url.getPort(), url.getScheme())) .cookieStore(new CookieStore() { // Noop cookie store. public void addCookie(Cookie arg0) { } public void clear() { } public boolean clearExpired(Date arg0) { return false; } public List<Cookie> getCookies() { return Collections.emptyList(); } }); } }