command.java

使用Java语言编写模拟路由器程序

				ObjectInputStream ois;
				ObjectOutputStream oos;

				ois = new ObjectInputStream(s.getInputStream());
				oos = new ObjectOutputStream(s.getOutputStream());

				// send the command
				oos.writeObject("step");

				// receive the response
				result = (String) ois.readObject();
				ois.close();
				oos.close();
				s.close();
			}

			return (result);
		} catch (NumberFormatException nfe) {
			return ("Found Invalid Router Id");
		} catch (Exception ioe) {
			return ("An I/O error occured while communication with Router " + routerId);
		}
	}

	/*
	 * Method Name: update
	 * 
	 * @args: the arguments to the update command
	 * 
	 * Use: to update the weight of the link between two routers
	 */
	String update(String args) {
		String[] fields;
		int routerId;
		Socket s;

		try {
			fields = args.split(",");

			if (fields.length != 3) {
				return ("Invalid args: " + args);
			}

			// get the source router
			routerId = Integer.parseInt(fields[0]);

			if (rl.contains(routerId) == false) {
				return ("Router with ID " + fields[0] + " not found in the Router Location Table");
			}
			if (activeRouters.contains(new Integer(routerId)) == false) {
				return ("Router with ID " + routerId + " not in the list of currently active routers");
			}

			s = new Socket(rl.getIp(routerId), rl.getCommandPort(routerId));

			ObjectInputStream ois;
			ObjectOutputStream oos;

			ois = new ObjectInputStream(s.getInputStream());
			oos = new ObjectOutputStream(s.getOutputStream());

			// send the command
			oos.writeObject("updateto:" + fields[1] + ":" + fields[2]);

			// receive the response
			String result = fields[0] + ": " + (String) ois.readObject() + "\n";
			ois.close();
			oos.close();
			s.close();

			// get the destination router
			routerId = Integer.parseInt(fields[1]);

			if (rl.contains(routerId) == false) {
				return ("Router with ID " + fields[1] + " not found in the Router Location Table");
			}

			if (activeRouters.contains(new Integer(routerId)) == false) {
				return ("Router with ID " + routerId + " not in the list of currently active routers");
			}

			s = new Socket(rl.getIp(routerId), rl.getCommandPort(routerId));

			ois = new ObjectInputStream(s.getInputStream());
			oos = new ObjectOutputStream(s.getOutputStream());

			// send the command
			oos.writeObject("updatefrom:" + fields[0] + ":" + fields[2]);

			// read the response
			result += fields[1] + ": " + (String) ois.readObject();
			ois.close();
			oos.close();
			s.close();

			return (result);
		} catch (NumberFormatException nfe) {
			return ("Invalid Router ID: " + args);
		} catch (Exception ioe) {
			return ("An I/O error occured while communication with Router " + args);
		}
	}

	/*
	 * Method Name: deleteRouter
	 * 
	 * @args: the arguments to the deleteRouter command
	 * 
	 * Use: to delete a router from the network
	 */
	String deleteRouter(String args) {
		// check whether the router is in the list of active routers
		// check why multiple threads are getting created

		int routerId = -1;
		String result = new String("");
		Socket s;

		try {
			// get the router id
			routerId = Integer.parseInt(args);

			if (rl.contains(routerId) == false) {
				return ("Router with ID " + routerId + " not found in the Router Location Table");
			}

			Iterator i = activeRouters.iterator();

			// for all active routers
			while (i.hasNext()) {
				routerId = ((Integer) i.next()).intValue();

				if (rl.contains(routerId) == false) {
					result = result
							+ ("Router with ID " + routerId + " (currently in the list of active routers) not found in the Router Location Table\n");
				}

				if (activeRouters.contains(new Integer(routerId)) == false) {
					return ("Router with ID " + routerId + " not in the list of currently active routers");
				}
				s = new Socket(rl.getIp(routerId), rl.getCommandPort(routerId));

				ObjectInputStream ois;
				ObjectOutputStream oos;

				ois = new ObjectInputStream(s.getInputStream());
				oos = new ObjectOutputStream(s.getOutputStream());

				// send the command
				oos.writeObject("deleteRouter:" + args);

				// receive the response
				result = result + routerId + ": " + (String) ois.readObject()
						+ "\n";

				ois.close();
				oos.close();
				s.close();
			}
		} catch (NumberFormatException nfe) {
			return ("Found Invalid Router Id");
		} catch (Exception ioe) {
			return ("An I/O error occured while communication with Router " + routerId);
		}

		// remove the router from the list of active routers
		activeRouters.remove(new Integer(Integer.parseInt(args)));
		return (result);
	}

	/*
	 * Method Name: start
	 * 
	 * @s: flag to indicate whether or not to wait for the user to press
	 * 'return' before the execution of the command Use: To perform a sequential
	 * execution of commands in the event file
	 */
	void start(boolean s) {
		DataInputStream d = new DataInputStream(System.in);

		try {
			// open the logfile
			BufferedWriter out = new BufferedWriter(new FileWriter(logfile));
			String result;

			Iterator i = commands.iterator();

			// for each command
			while (i.hasNext()) {
				String command = (String) i.next();

				String[] fields = command.split(":", 2);

				if (s == true) {
					System.out
							.print("Press any key to execute the next command ("
									+ command + ") ");
					try {
						d.readByte();
					} catch (Exception e) {
						System.out
								.println("An error occured while reading from the standard input");
						System.out.println("Quitting.");
						System.exit(1);
					}

					System.out.println("");
				}

				// print the command to the screen and the logfile
				System.out.println("[" + command + "]");
				out.write("[" + command + "]\n");

				if (fields.length != 2) {
					System.out.println("\nInvalid Command\n");

					out.write("\nInvalid Arguments\n");
				}

				else if (fields[0].equals("addRouter")) {
					result = addRouter(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else if (fields[0].equals("deleteRouter")) {
					result = deleteRouter(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else if (fields[0].equals("update")) {
					result = update(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else if (fields[0].equals("packets")) {
					result = getPackets(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else if (fields[0].equals("route")) {
					result = getRoute(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else if (fields[0].equals("display")) {
					result = displayRoutingTable(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else if (fields[0].equals("step")) {
					result = step(fields[1]);

					System.out.println(result);
					out.write(result + "\n");
				}

				else {
					System.out.println("\nInvalid Command\n");
					out.write("\nInvalid Command\n");
				}
			}

			out.close();
		} catch (IOException ioe) {
			System.out.println("Unable to write to the log file: " + logfile);
			System.out.println("Quitting.");

			System.exit(1);
		}

		return;

	}

	/*
	 * Method Name: main
	 * 
	 * @args: The command line arguments
	 * 
	 * Use: To start the execution of the command program
	 */
	public static void main(String[] args) {
		String ef = "event.txt";
		String rlf = "rlf.txt";
		String of = "log.txt";
		String tcf = "tcf.txt";

		int id = -1;
		boolean s = false;

		if (args.length == 0) {
			System.out.println("Usage: java Command <options>");
			System.out.println("where possible options include:");
			System.out.println(" -h       : Print a synopsis of options");
			System.out
					.println(" -f <ef>  : Override the default Event File (ef.txt)");
			System.out
					.println(" -l <rlf> : Override the default Router Location File (rlf.txt)");
			System.out
					.println(" -t <tcf> : Override the default Topology Configuration File (tcf.txt)");
			System.out
					.println(" -o <of>  : Override the default Output File (log.txt)");
			System.out.println(" -s       : To 'step' through the events");
			System.exit(1);
		}

		else {
			for (int i = 0; i < (args.length); i++) {
				if (args[i].equals("-h")) {
					System.out.println("Usage: java Command <options>");
					System.out.println("where possible options include:");
					System.out
							.println(" -h       : Print a synopsis of options");
					System.out
							.println(" -f <ef>  : Override the default Event File (ef.txt)");
					System.out
							.println(" -l <rlf> : Override the default Router Location File (rlf.txt)");
					System.out
							.println(" -t <tcf> : Override the default Topology Configuration File (tcf.txt)");
					System.out
							.println(" -o <of>  : Override the default Output File (log.txt)");
					System.out
							.println(" -s       : To 'step' through the events");
					System.exit(0);
				}

				else if (args[i].equals("-s")) {
					s = true;
				}

				else if (args[i].equals("-f")) {
					if (i == (args.length - 1)) {
						System.out
								.println("Please specify the value for option '-f'");
						System.exit(1);
					} else {
						ef = args[i + 1];
						i++;
					}
				}

				else if (args[i].equals("-l")) {
					if (i == (args.length - 1)) {
						System.out
								.println("Please specify the value for option '-l'");
						System.exit(1);
					} else {
						rlf = args[i + 1];
						i++;
					}
				}

				else if (args[i].equals("-o")) {
					if (i == (args.length - 1)) {
						System.out
								.println("Please specify the value for option '-o'");
						System.exit(1);
					} else {
						of = args[i + 1];
						i++;
					}
				}

				else if (args[i].equals("-t")) {
					if (i == (args.length - 1)) {
						System.out
								.println("Please specify the value for option '-t'");
						System.exit(1);
					} else {
						tcf = args[i + 1];
						i++;
					}
				}

				else {
					System.out.println("Invalid option " + args[i]);
					System.exit(1);
				}

			}

			Command c = new Command(ef, rlf, of, tcf);
			c.start(s);
		}
	}
}