- * It represents a single action: a client is expected to only execute one - * action, while a server is expected to execute one action for each client - * action. - * - * @author niki - */ -abstract class ConnectAction { - private Socket s; - private boolean server; - private Version version; - private Version clientVersion; - - private Object lock = new Object(); - private BufferedReader in; - private OutputStreamWriter out; - private boolean contentToSend; - - /** - * Method that will be called when an action is performed on either the - * client or server this {@link ConnectAction} represent. - * - * @param version - * the counter part version - * - * @throws Exception - * in case of I/O error - */ - abstract protected void action(Version version) throws Exception; - - /** - * Method called when we negotiate the version with the client. - *
- * Thus, it is only called on the server. - *
- * Will return the actual server version by default. - * - * @param clientVersion - * the client version - * - * @return the version to send to the client - */ - abstract protected Version negotiateVersion(Version clientVersion); - - /** - * Handler called when an unexpected error occurs in the code. - * - * @param e - * the exception that occurred - */ - abstract protected void onError(Exception e); - - /** - * Create a new {@link ConnectAction}. - * - * @param s - * the socket to bind to - * @param server - * TRUE for a server action, FALSE for a client action (will - * impact the process) - * @param version - * the version of this client-or-server - */ - protected ConnectAction(Socket s, boolean server, Version version) { - this.s = s; - this.server = server; - - if (version == null) { - this.version = new Version(); - } else { - this.version = version; - } - - clientVersion = new Version(); - } - - /** - * The version of this client-or-server. - * - * @return the version - */ - public Version getVersion() { - return version; - } - - /** - * Actually start the process (this is synchronous). - */ - public void connect() { - try { - in = new BufferedReader(new InputStreamReader(s.getInputStream(), - "UTF-8")); - try { - out = new OutputStreamWriter(s.getOutputStream(), "UTF-8"); - try { - if (server) { - action(clientVersion); - } else { - String v = sendString("VERSION " + version.toString()); - if (v != null && v.startsWith("VERSION ")) { - v = v.substring("VERSION ".length()); - } - - action(new Version(v)); - } - } finally { - out.close(); - } - } finally { - in.close(); - } - } catch (Exception e) { - onError(e); - } finally { - try { - s.close(); - } catch (Exception e) { - onError(e); - } - } - } - - /** - * Serialise and send the given object to the counter part (and, only for - * client, return the deserialised answer -- the server will always receive - * NULL). - * - * @param data - * the data to send - * - * @return the answer (which can be NULL) if this action is a client, always - * NULL if it is a server - * - * @throws IOException - * in case of I/O error - * @throws NoSuchFieldException - * if the serialised data contains information about a field - * which does actually not exist in the class we know of - * @throws NoSuchMethodException - * if a class described in the serialised data cannot be created - * because it is not compatible with this code - * @throws ClassNotFoundException - * if a class described in the serialised data cannot be found - */ - protected Object send(Object data) throws IOException, - NoSuchFieldException, NoSuchMethodException, ClassNotFoundException { - synchronized (lock) { - String rep = sendString(new Exporter().append(data).toString(true)); - if (rep != null) { - return new Importer().read(rep).getValue(); - } - - return null; - } - } - - /** - * Reserved for the server: flush the data to the client and retrieve its - * answer. - *
- * Also used internally for the client (only do something if there is - * contentToSend). - *
- * Will only flush the data if there is contentToSend. - * - * @return the deserialised answer (which can actually be NULL) - * - * @throws IOException - * in case of I/O error - * @throws NoSuchFieldException - * if the serialised data contains information about a field - * which does actually not exist in the class we know of - * @throws NoSuchMethodException - * if a class described in the serialised data cannot be created - * because it is not compatible with this code - * @throws ClassNotFoundException - * if a class described in the serialised data cannot be found - * @throws java.lang.NullPointerException - * if the counter part has no data to send - */ - protected Object rec() throws IOException, NoSuchFieldException, - NoSuchMethodException, ClassNotFoundException, - java.lang.NullPointerException { - String str = flushString(); - if (str == null) { - throw new NullPointerException("No more data available"); - } - - return new Importer().read(str).getValue(); - } - - /** - * Send the given string to the counter part (and, only for client, return - * the answer -- the server will always receive NULL). - * - * @param line - * the data to send (we will add a line feed) - * - * @return the answer if this action is a client (without the added line - * feed), NULL if it is a server - * - * @throws IOException - * in case of I/O error - */ - protected String sendString(String line) throws IOException { - synchronized (lock) { - out.write(line); - out.write("\n"); - - if (server) { - out.flush(); - return null; - } - - contentToSend = true; - return flushString(); - } - } - - /** - * Reserved for the server (externally): flush the data to the client and - * retrieve its answer. - *
- * Also used internally for the client (only do something if there is - * contentToSend). - *
- * Will only flush the data if there is contentToSend. - * - * @return the answer (which can be NULL) - * - * @throws IOException - * in case of I/O error - */ - protected String flushString() throws IOException { - synchronized (lock) { - if (server || contentToSend) { - if (contentToSend) { - out.flush(); - contentToSend = false; - } - - String line = in.readLine(); - if (server && line != null && line.startsWith("VERSION ")) { - // "VERSION client-version" (VERSION 1.0.0) - Version clientVersion = new Version( - line.substring("VERSION ".length())); - this.clientVersion = clientVersion; - Version v = negotiateVersion(clientVersion); - if (v == null) { - v = new Version(); - } - sendString("VERSION " + v.toString()); - - line = in.readLine(); - } - - return line; - } - - return null; - } - } -} \ No newline at end of file