Java tutorial
/* * Copyright (C) 2007 ETH Zurich * * This file is part of Accada (www.accada.org). * * Accada is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License version 2.1, as published by the Free Software Foundation. * * Accada 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 Accada; if not, write to the Free * Software Foundation, Inc., 51 Franklin Street, Fifth Floor, * Boston, MA 02110-1301 USA */ package org.accada.reader.hal.impl.sim; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.Socket; import java.net.UnknownHostException; import java.util.Properties; import org.accada.reader.hal.HardwareException; import org.accada.reader.hal.impl.sim.multi.SimulatorServerException; import org.accada.reader.hal.impl.sim.multi.SimulatorServerTokens; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * @author regli */ public class SimulatorClient extends Thread implements SimulatorEngine { /** the logger */ private static final Log LOG = LogFactory.getLog(SimulatorClient.class); private static final String PROPERTIES_FILE_LOCATION = "/props/SimulatorClient.properties"; private final String host; private final int port; private final int timeout; private final int waittime; private SimulatorController controller; private OutputStream out; private InputStream in; private boolean unkownHost; private boolean connected; public SimulatorClient() throws SimulatorServerException { // load properties from properties file Properties props; try { props = new Properties(); props.load(this.getClass().getResourceAsStream(PROPERTIES_FILE_LOCATION)); } catch (IOException e) { throw new SimulatorServerException("Could not load property file."); } // check properties if (!props.containsKey("host")) { throw new SimulatorServerException("Property 'host' not found."); } if (!props.containsKey("port")) { throw new SimulatorServerException("Property 'port' not found."); } if (!props.containsKey("timeout")) { throw new SimulatorServerException("Property 'timeout' not found."); } if (!props.containsKey("waittime")) { throw new SimulatorServerException("Property 'waittime' not found."); } // get properties host = props.getProperty("host"); try { port = Integer.parseInt(props.getProperty("port")); timeout = Integer.parseInt(props.getProperty("timeout")); waittime = Integer.parseInt(props.getProperty("waittime")); } catch (NumberFormatException e) { throw new SimulatorServerException("Properties 'port', 'timeout' and 'waittime' must be numbers"); } } public void initialize(SimulatorController controller) throws SimulatorServerException { this.controller = controller; tryToConnect(); } public void run() { while (connected) { try { while (true) { generateEvent(getInput()); } } catch (IOException e) { try { tryToConnect(); } catch (SimulatorServerException e1) { LOG.error(e1.getMessage()); LOG.error("could not connect"); } } } } public boolean contains(String antennaId, String tagId) { return controller.contains(antennaId, tagId); } private void tryToConnect() throws SimulatorServerException { LOG.info("SimulatorServer tries to connect to SimulatorServerController."); connected = false; if (connect()) { connected = true; } else { int i = 1; int nbrOfLoops = waittime > 0 ? timeout / waittime : 0; while (!connected && !unkownHost && i < nbrOfLoops) { try { Thread.sleep(waittime); } catch (InterruptedException e) { e.printStackTrace(); } connected = connect(); i++; } } // register if connection is up if (connected) { LOG.info("SimulatorServer is connected to SimulatorServerController."); // start if register was successful and thread is not already started if (register()) { if (!isAlive()) { start(); } } else { throw new SimulatorServerException("Could not register"); } } else { throw new SimulatorServerException("Could not connect to the server. (timeout = " + timeout + "ms)"); } } private boolean connect() { Socket socket; try { socket = new Socket(host, port); out = socket.getOutputStream(); in = socket.getInputStream(); unkownHost = false; return true; } catch (UnknownHostException e) { unkownHost = true; LOG.info("Unknown host."); return false; } catch (IOException e) { LOG.info("Connection refused."); return false; } } private boolean register() { String readerId = controller.getHalName(); String[] antennaIds = null; try { antennaIds = controller.getReadPointNames(); } catch (HardwareException ignored) { } try { out.write((readerId + SimulatorServerTokens.EOH).getBytes()); for (int i = 0; i < antennaIds.length; i++) { out.write(antennaIds[i].getBytes()); if (i + 1 < antennaIds.length) { out.write(SimulatorServerTokens.DELIMITER.getBytes()); } } out.write(SimulatorServerTokens.EOL); out.flush(); return true; } catch (IOException e) { return false; } } private void sendAlive() throws IOException { out.write(SimulatorServerTokens.ALIVE.getBytes()); out.flush(); } private String getInput() throws IOException { StringBuffer input = new StringBuffer(); int buf = in.read(); do { input.append((char) buf); buf = in.read(); } while ((char) buf != SimulatorServerTokens.EOL); return input.toString(); } private void generateEvent(String input) { String[] fragments = input.split(SimulatorServerTokens.EOH); if (fragments.length == 1) { if (SimulatorServerTokens.PING.equals(input)) { try { sendAlive(); } catch (IOException e) { e.printStackTrace(); } } else { throw new IllegalArgumentException(); } } else if (fragments.length == 2) { String type = fragments[0]; fragments = fragments[1].split(SimulatorServerTokens.DELIMITER); if (fragments.length == 2) { String antennaId = fragments[0]; String tagId = fragments[1]; if (SimulatorServerTokens.ADD.equals(type)) { controller.add(antennaId, tagId); } else if (SimulatorServerTokens.REMOVE.equals(type)) { controller.remove(antennaId, tagId); } } else { throw new IllegalArgumentException(); } } else { throw new IllegalArgumentException(); } } }