Java tutorial
/** * FreifunkNodePushServlet * Copyright 16.07.2015 by Dang Hai An, @zyzo * <p/> * 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. * <p/> * 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. * <p/> * 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.iot; import org.eclipse.jetty.util.log.Log; import org.json.JSONArray; import org.json.JSONObject; import org.loklak.data.DAO; import org.loklak.geo.LocationSource; import org.loklak.harvester.JsonFieldConverter; import org.loklak.http.ClientConnection; import org.loklak.http.RemoteAccess; import org.loklak.objects.SourceType; import org.loklak.server.Query; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.InputSource; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import java.io.IOException; import java.io.StringReader; import java.util.ArrayList; import java.util.List; import java.util.Arrays; public class NetmonPushServlet extends HttpServlet { private static final long serialVersionUID = 1423618084632135238L; @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Query post = RemoteAccess.evaluate(request); String remoteHash = Integer.toHexString(Math.abs(post.getClientHost().hashCode())); // manage DoS if (post.isDoS_blackout()) { response.sendError(503, "your request frequency is too high"); return; } String url = post.get("url", ""); if (url == null || url.length() == 0) { response.sendError(400, "your request does not contain an url to your data object"); return; } String screen_name = post.get("screen_name", ""); if (screen_name == null || screen_name.length() == 0) { response.sendError(400, "your request does not contain required screen_name parameter"); return; } JSONArray nodesList = new JSONArray(); byte[] xmlText; try { xmlText = ClientConnection.download(url); DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document document = builder.parse(new InputSource(new StringReader(new String(xmlText)))); NodeList routerList = document.getElementsByTagName("router"); for (int i = 0; i < routerList.getLength(); i++) { JSONObject node = convertDOMNodeToMap(routerList.item(i)); if (node != null) nodesList.put(node); } } catch (Exception e) { Log.getLog().warn(e); response.sendError(400, "error reading json file from url"); return; } JsonFieldConverter converter = new JsonFieldConverter( JsonFieldConverter.JsonConversionSchemaEnum.NETMON_NODE); JSONArray nodes = converter.convert(nodesList); for (Object node_obj : nodes) { JSONObject node = (JSONObject) node_obj; if (!node.has("text")) { node.put("text", ""); } node.put("source_type", SourceType.NETMON.toString()); if (!node.has("user")) { node.put("user", new JSONObject()); } List<Object> location_point = new ArrayList<>(); location_point.add(0, Double.parseDouble((String) node.get("latitude"))); location_point.add(1, Double.parseDouble((String) node.get("longitude"))); node.put("location_point", location_point); node.put("location_mark", location_point); node.put("location_source", LocationSource.USER.name()); try { node.put("id_str", PushServletHelper.computeMessageId(node, SourceType.NETMON)); } catch (Exception e) { DAO.log("Problem computing id" + e.getMessage()); continue; } try { JSONObject user = (JSONObject) node.get("user"); user.put("screen_name", computeUserId(user.get("update_date"), user.get("id"), SourceType.NETMON)); } catch (Exception e) { DAO.log("Problem computing user id : " + e.getMessage()); } } PushReport pushReport = PushServletHelper.saveMessagesAndImportProfile(nodes, Arrays.hashCode(xmlText), post, SourceType.NETMON, screen_name); String res = PushServletHelper.buildJSONResponse(post.get("callback", ""), pushReport); response.getOutputStream().println(res); DAO.log(request.getServletPath() + " -> records = " + pushReport.getRecordCount() + ", new = " + pushReport.getNewCount() + ", known = " + pushReport.getKnownCount() + ", from host hash " + remoteHash); } private static JSONObject convertDOMNodeToMap(Node node) { Node directChild = node.getFirstChild(); if (directChild == null) { return null; } JSONObject result = new JSONObject(true); while (directChild != null) { if (directChild.getChildNodes().getLength() == 1 && directChild.getChildNodes().item(0).getNodeType() == Node.TEXT_NODE) { result.put(directChild.getNodeName(), directChild.getChildNodes().item(0).getTextContent()); } else { result.put(directChild.getNodeName(), convertDOMNodeToMap(directChild)); } directChild = directChild.getNextSibling(); } return result; } private static String computeUserId(Object mtime, Object initialId, SourceType sourceType) throws Exception { if (mtime == null) { throw new Exception("mtime field is missing"); } boolean hasId = initialId != null && !initialId.equals(""); return sourceType.toString() + "_" + (hasId ? initialId + "_" : "") + mtime; } }