Java tutorial
/** * Squidy Interaction 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 3 of the License, * or (at your option) any later version. * * Squidy Interaction 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 Squidy Interaction Library. If not, see * <http://www.gnu.org/licenses/>. * * 2009 Human-Computer Interaction Group, University of Konstanz. * <http://hci.uni-konstanz.de> * * Please contact info@squidy-lib.de or visit our website * <http://www.squidy-lib.de> for further information. */ package org.squidy.nodes.tracking.configclient.service.comm; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.ConnectException; import java.net.InetSocketAddress; import java.net.Socket; import java.net.UnknownHostException; import javax.xml.bind.JAXBContext; import javax.xml.bind.JAXBException; import javax.xml.bind.Marshaller; import javax.xml.bind.Unmarshaller; import javax.xml.stream.XMLEventReader; import javax.xml.stream.XMLInputFactory; import javax.xml.stream.XMLOutputFactory; import javax.xml.stream.XMLStreamException; import javax.xml.stream.XMLStreamWriter; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.squidy.nodes.tracking.config.xml.Configuration; import org.squidy.nodes.tracking.configclient.service.Service; import org.squidy.nodes.tracking.configclient.service.ServiceRegistry; import org.squidy.nodes.tracking.configclient.service.javaprop.JavaPropService; public class TcpIpCommService extends CommService { // Logger to log info, error, debug,... messages. private static Log LOG = LogFactory.getLog(TcpIpCommService.class); private static final String PROTOCOL_ELEM = "protocol"; private static final String PROTOCOL_COMMENT = "config"; // services private JavaPropService pService = (JavaPropService) ServiceRegistry.getInstance() .getService(JavaPropService.class); // stuff for debugging private boolean debug = false; private static final String DEBUGFILE_IN = "debugfile_in.xml"; private static final String DEBUGFILE_OUT = "debugfile_out.xml"; private FileOutputStream debugFos_in; private FileOutputStream debugFos_out; // connection private InetSocketAddress address; private Socket server; // xml processor private XMLStreamWriter xsw; private XMLEventReader xer; // jaxb private JAXBContext context; private Unmarshaller unmarshaller; private Marshaller marshaller; public TcpIpCommService(InetSocketAddress s) { this.address = s; } @Override protected void startupImpl() throws CommException { Object property = pService.getProperties().getProperty(JavaPropService.DEBUG_COMM); if (property != null) { debug = Boolean.parseBoolean((String) property); } if (debug) initDebugOutput(); // init connection LOG.info("Creating connection: " + address); try { server = new Socket(address.getAddress(), address.getPort()); LOG.info("Connection accepted"); newConnection(server.getInputStream(), server.getOutputStream()); } catch (ConnectException e) { String msg = "Connection to " + address + " refused."; LOG.error(msg); throw new CommException(msg); } catch (UnknownHostException e) { String msg = "Unknown host: " + address; LOG.error(msg); throw new CommException(msg); } catch (IOException e) { String msg = "Cannot read from: " + address; LOG.error(msg); throw new CommException(msg); } // init jaxb try { context = JAXBContext.newInstance(Configuration.class.getPackage().getName()); unmarshaller = context.createUnmarshaller(); marshaller = context.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true); } catch (JAXBException e) { LOG.error(e.getMessage(), e); throw new CommException(CommService.INTERNAL_ERROR_MSG); } } private void initDebugOutput() { LOG.info("Creating debug files: " + DEBUGFILE_IN + " " + DEBUGFILE_OUT); try { debugFos_in = new FileOutputStream(DEBUGFILE_IN); debugFos_out = new FileOutputStream(DEBUGFILE_OUT); } catch (FileNotFoundException e1) { e1.printStackTrace(); } } private void newConnection(InputStream in, OutputStream out) throws CommException { try { xsw = XMLOutputFactory.newInstance().createXMLStreamWriter(out); xsw.writeStartDocument(); xsw.writeStartElement(PROTOCOL_ELEM); xsw.writeComment(PROTOCOL_COMMENT); // arbitrary xsw.flush(); xer = XMLInputFactory.newInstance().createXMLEventReader(in); xer.nextEvent(); // startDocument xer.nextTag(); // protocol element TODO: protocol check xer.nextEvent(); // arbitrary comment } catch (Exception e) { // XMLStreamException // FactoryConfigurationError String msg = "Unable to initialize protocol."; LOG.error(msg, e); throw new CommException(msg); } } @Override protected Configuration loadConfigImpl() throws CommException { assert (server != null); LOG.info("Receiving config"); Configuration config; try { config = (Configuration) unmarshaller.unmarshal(xer); if (debug) { marshaller.marshal(config, System.out); } } catch (Exception e) { String msg = "Unable to load configuration (JAXB)."; LOG.error(msg, e); throw new CommException(msg); } return config; } @Override protected Configuration saveConfigImpl(Configuration config) throws CommException { assert (server != null); LOG.info("Sending config"); try { // send if (debug) marshaller.marshal(config, debugFos_out); marshaller.marshal(config, xsw); xsw.flush(); // receive config = (Configuration) unmarshaller.unmarshal(xer); if (debug) marshaller.marshal(config, debugFos_in); } catch (JAXBException e) { String msg = "Unable to save configuration (JAXB)."; LOG.error(msg, e); throw new CommException(msg); } catch (XMLStreamException e) { String msg = "Unable to save configuration (XML)."; LOG.error(msg, e); throw new CommException(msg); } return config; } @Override protected void shutdownImpl() { LOG.info("Closing connection."); if (xsw != null) { try { xsw.writeEndDocument(); xsw.close(); } catch (XMLStreamException ignore) { } } if (xer != null) { try { xer.close(); } catch (XMLStreamException ignore) { } ; } if (server != null) { try { server.close(); } catch (IOException ignore) { } ; } if (debug) { if (debugFos_in != null) { try { debugFos_in.close(); } catch (IOException ignore) { } ; } if (debugFos_out != null) { try { debugFos_out.close(); } catch (IOException ignore) { } ; } } } @Override public Class<? extends Service> getServiceType() { return CommService.class; } }