Java tutorial
/** * ProxyServlet * Copyright 12.06.2015 by Michael Peter Christen, @0rb1t3r * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program in the file lgpl21.txt * If not, see <http://www.gnu.org/licenses/>. */ package org.loklak.api.cms; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.eclipse.jetty.util.log.Log; import org.json.JSONObject; import org.loklak.data.DAO; import org.loklak.data.IndexEntry; import org.loklak.harvester.TwitterAPI; import org.loklak.http.ClientConnection; import org.loklak.http.RemoteAccess; import org.loklak.objects.UserEntry; import org.loklak.server.Query; import org.loklak.tools.CacheMap; import twitter4j.TwitterException; public class ProxyServlet extends HttpServlet { private static final long serialVersionUID = -9112326722297824443L; private final static CacheMap<String, byte[]> cache = new CacheMap<>(1000); @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Query post = RemoteAccess.evaluate(request); if (post.isDoS_blackout()) { response.sendError(503, "your request frequency is too high"); return; } // DoS protection process(request, response, post); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Query post = RemoteAccess.evaluate(request); if (post.isDoS_blackout()) { response.sendError(503, "your request frequency is too high"); return; } // DoS protection post.initPOST(RemoteAccess.getPostMap(request)); process(request, response, post); } // http://localhost:9000/api/proxy.png?screen_name=loklak_app&url=https://pbs.twimg.com/profile_images/577512240640733184/fizL4YIn_bigger.png protected void process(HttpServletRequest request, HttpServletResponse response, Query post) throws ServletException, IOException { // parse arguments String url = post.get("url", ""); String screen_name = post.get("screen_name", ""); DAO.log("PROXY: called with screen_name=" + screen_name + ", url=" + url); if (screen_name.length() == 0 && (url.length() == 0 || screen_name.indexOf("twimg.com") < 0)) { response.sendError(503, "either attributes url or screen_name or both must be submitted"); return; } byte[] buffer = url.length() == 0 ? null : cache.get(url); if (buffer != null) DAO.log("PROXY: got url=" + url + " content from ram cache!"); UserEntry user = null; if (buffer == null && screen_name.length() > 0) { if (buffer == null && (url.length() == 0 || isProfileImage(url))) { // try to read it from the user profiles user = DAO.searchLocalUserByScreenName(screen_name); if (user != null) { buffer = user.getProfileImage(); if (buffer != null) DAO.log("PROXY: got url=" + url + " content from user profile bas64 cache!"); if (url.length() == 0) url = user.getProfileImageUrl(); cache.put(user.getProfileImageUrl(), buffer); } } } if (buffer == null && url.length() > 0) { // try to download the image buffer = ClientConnection.download(url); String newUrl = user == null ? null : user.getProfileImageUrl(); if (buffer != null) { DAO.log("PROXY: downloaded given url=" + url + " successfully!"); } else if (newUrl != null && !newUrl.equalsIgnoreCase(url)) { // if this fails, then check if the stored url is different. // That may happen because new user avatar images get new urls buffer = ClientConnection.download(newUrl); if (buffer != null) DAO.log("PROXY: downloaded url=" + url + " from old user setting successfully!"); } if (buffer == null) { // ask the Twitter API for new user data try { JSONObject usermap = TwitterAPI.getUser(screen_name, true); newUrl = usermap.has("profile_image_url") ? (String) usermap.get("profile_image_url") : null; if (newUrl != null && newUrl.length() > 0 && !newUrl.startsWith("http:") && usermap.has("profile_image_url_https")) newUrl = (String) usermap.get("profile_image_url_https"); if (newUrl != null && newUrl.length() > 0) buffer = ClientConnection.download(newUrl); if (buffer != null) DAO.log("PROXY: downloaded url=" + url + " from recently downloaded user setting successfully!"); } catch (TwitterException e) { DAO.log("ProxyServlet: call to twitter api failed: " + e.getMessage()); } } if (buffer != null) { // write the buffer if (user != null) { user.setProfileImageUrl(newUrl); user.setProfileImage(buffer); try { // record user into search index DAO.users.writeEntry(new IndexEntry<UserEntry>(user.getScreenName(), user.getType(), user)); } catch (IOException e) { Log.getLog().warn(e); } if (!cache.full()) cache.put(url, buffer); } else { cache.put(url, buffer); } } } if (buffer == null) { if (screen_name.length() == 0) { response.sendError(503, "url cannot be loaded"); return; } if (url.length() == 0) { response.sendError(503, "user cannot be found"); return; } response.sendError(503, "url cannot be loaded and user cannot be found"); return; } if (url.endsWith(".png") || (url.length() == 0 && request.getServletPath().endsWith(".png"))) post.setResponse(response, "image/png"); else if (url.endsWith(".gif") || (url.length() == 0 && request.getServletPath().endsWith(".gif"))) post.setResponse(response, "image/gif"); else if (url.endsWith(".jpg") || url.endsWith(".jpeg") || (url.length() == 0 && request.getServletPath().endsWith(".jpg"))) post.setResponse(response, "image/jpeg"); else post.setResponse(response, "application/octet-stream"); ServletOutputStream sos = response.getOutputStream(); sos.write(buffer); post.finalize(); } private boolean isProfileImage(String url) { return url.indexOf("pbs.twimg.com/profile_images") > 0 && url.endsWith("_bigger.png"); } }