routerlocation.java

使用Java语言编写模拟路由器程序

/* File: RouterLocation.java
 *
 * This file contains the code for the class RouterLocation,
 * which represents the Router Location File
 *
 * The Command and the Router programs use this when they want to communicate
 * with the routers in the network
 */
import java.net.*;
import java.util.*;
import java.util.regex.*;
import java.io.*;

class RouterLocation {
	// a set of entries, each entry containing information about a router
	HashSet entries;

	/*
	 * Constructor
	 * 
	 * @filename: The name of the Router Location File
	 * 
	 * Use: To read the Router Location file and initialize the list of entries
	 */
	public RouterLocation(String filename) {
		entries = new HashSet();

		BufferedReader in = null;

		// open the file for reading
		try {
			in = new BufferedReader(new FileReader(filename));
		} catch (IOException e) {
			System.out.println("Unable to open file: " + filename);
			System.out.println("Quitting.");
			System.exit(1);
		}

		try {
			String[] fields;
			String line;

			InetAddress ip = null;
			int commandPort = -1;
			int routerPort = -1;
			int routerId = -1;

			int linenumber = 1;

			// read a line from the file
			line = in.readLine();

			while (line != null) {

				if (line.equals("") == false) {
					try {
						// split this line using "," as a delimiter
						fields = line.split(",");

						if (fields.length != 4) {
							System.out.println("Line " + linenumber
									+ " in file " + filename
									+ " : Invalid entry");
							System.out.println("Quitting.");

							System.exit(1);
						}

						// get the individual elements - the IP, command and
						// router ports, and the router Id
						ip = InetAddress.getByName(fields[0]);
						commandPort = Integer.parseInt(fields[1]);
						routerPort = Integer.parseInt(fields[2]);
						routerId = Integer.parseInt(fields[3]);
					}

					catch (PatternSyntaxException pse) {
						System.out.println("Pattern Syntax Exception in RouterLocation.java");
						System.out.println("Quitting.");

						System.exit(1);
					}

					// invalid entries in the file
					catch (NumberFormatException nfe) {
						System.out.println("Line number " + linenumber + " in file " + filename + ": Invalid number");
						System.out.println("Quitting.");

						System.exit(1);
					}

					// invalid IP address
					catch (UnknownHostException uhe) {
						System.out.println("Line number " + linenumber + " in file " + filename + ": Invalid IP");
						System.out.println("Quitting.");

						System.exit(1);
					}

					// add the entry to the list
					entries.add(new RouterLocationEntry(ip, commandPort, routerPort, routerId));
				}

				linenumber++;

				line = in.readLine();
			}

			in.close();
		} catch (IOException ioe) {
			System.out.println("I/O error occured while reading from the file: " + filename);
			System.out.println("Quitting.");

			System.exit(1);
		}

		return;
	}

	/*
	 * Method Name: getIp
	 * 
	 * @id: the id of the router whose IP is required
	 * 
	 * Use: This is used to get the IP address of a router, given its Id
	 */
	InetAddress getIp(int id) {
		RouterLocationEntry r;

		Iterator i = entries.iterator();

		while (i.hasNext()) {
			r = (RouterLocationEntry) i.next();

			if (r.getRouterId() == id) {
				return r.getIp();
			}
		}

		return null;
	}

	/*
	 * Method Name: getCommandPort
	 * 
	 * @id: the id of the router whose command port is required
	 * 
	 * Use: This is used to get the command port of a router, given its Id
	 */
	int getCommandPort(int id) {
		RouterLocationEntry r;

		Iterator i = entries.iterator();

		while (i.hasNext()) {
			r = (RouterLocationEntry) i.next();

			if (r.getRouterId() == id) {
				return r.getCommandPort();
			}
		}

		return -1;
	}

	/*
	 * Method Name: getRouterPort
	 * 
	 * @id: the id of the router whose router port is required
	 * 
	 * Use: This is used to get the router port of a router, given its Id
	 */
	int getRouterPort(int id) {
		RouterLocationEntry r;

		Iterator i = entries.iterator();

		while (i.hasNext()) {
			r = (RouterLocationEntry) i.next();

			if (r.getRouterId() == id) {
				return r.getRouterPort();
			}
		}

		return -1;
	}

	/*
	 * Method Name: contains
	 * 
	 * @id: the id of a router
	 * 
	 * Use: Used to find whether an entry for a router with given Id exists in
	 * the list of entries
	 */
	boolean contains(int id) {
		Integer ID = new Integer(id);

		Iterator i = entries.iterator();

		while (i.hasNext()) {
			if (((RouterLocationEntry) i.next()).getRouterId() == id) {
				return true;
			}
		}

		return false;
	}

	/*
	 * Method Name: getRouterIds
	 * 
	 * Use: To get the list of all router id's in the list
	 */

	HashSet getRouterIds() {
		HashSet ids = new HashSet();

		Iterator i = entries.iterator();

		while (i.hasNext()) {
			ids.add(new Integer(((RouterLocationEntry) i.next()).getRouterId()));
		}

		return ids;
	}
}