Source code is available in KKsrc.zip
Server dialog:
C:\ece538\KnockKnock>java -jar KKServer.jar 4444
Server does not echo anything to the command window.
Client dialog:
C:\ece538\KnockKnock>java -jar KKClient.jar localhost 4444 Server: Knock! Knock! Client: Who's there? Server: Turnip Client: Turnip who? Server: Turnip the heat, it's cold in here! Want another? (y/n) Client: n Server: Bye.
KnockKnockClient.java
import java.io.*; import java.net.*; public class KnockKnockClient { public static void main(String[] args) throws IOException { if (args.length != 2) { System.err.println( "Usage: java EchoClient <host name> <port number>"); System.exit(1); } String hostName = args[0]; int portNumber = Integer.parseInt(args[1]); try ( Socket kkSocket = new Socket(hostName, portNumber); PrintWriter out = new PrintWriter(kkSocket.getOutputStream(), true); BufferedReader in = new BufferedReader( new InputStreamReader(kkSocket.getInputStream())); ) { BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in)); String fromServer; String fromUser; while ((fromServer = in.readLine()) != null) { System.out.println("Server: " + fromServer); if (fromServer.equals("Bye.")) break; fromUser = stdIn.readLine(); if (fromUser != null) { System.out.println("Client: " + fromUser); out.println(fromUser); } } } catch (UnknownHostException e) { System.err.println("Don't know about host " + hostName); System.exit(1); } catch (IOException e) { System.err.println("Couldn't get I/O for the connection to " + hostName); System.exit(1); } } }
KnockKnockProtocol.java
import java.net.*; import java.io.*; public class KnockKnockProtocol { private static final int WAITING = 0; private static final int SENTKNOCKKNOCK = 1; private static final int SENTCLUE = 2; private static final int ANOTHER = 3; private static final int NUMJOKES = 5; private int state = WAITING; private int currentJoke = 0; private String[] clues = { "Turnip", "Little Old Lady", "Atch", "Who", "Who" }; private String[] answers = { "Turnip the heat, it's cold in here!", "I didn't know you could yodel!", "Bless you!", "Is there an owl in here?", "Is there an echo in here?" }; public String processInput(String theInput) { String theOutput = null; if (state == WAITING) { theOutput = "Knock! Knock!"; state = SENTKNOCKKNOCK; } else if (state == SENTKNOCKKNOCK) { if (theInput.equalsIgnoreCase("Who's there?")) { theOutput = clues[currentJoke]; state = SENTCLUE; } else { theOutput = "You're supposed to say \"Who's there?\"! " + "Try again. Knock! Knock!"; } } else if (state == SENTCLUE) { if (theInput.equalsIgnoreCase(clues[currentJoke] + " who?")) { theOutput = answers[currentJoke] + " Want another? (y/n)"; state = ANOTHER; } else { theOutput = "You're supposed to say \"" + clues[currentJoke] + " who?\"" + "! Try again. Knock! Knock!"; state = SENTKNOCKKNOCK; } } else if (state == ANOTHER) { if (theInput.equalsIgnoreCase("y")) { theOutput = "Knock! Knock!"; if (currentJoke == (NUMJOKES - 1)) currentJoke = 0; else currentJoke++; state = SENTKNOCKKNOCK; } else { theOutput = "Bye."; state = WAITING; } } return theOutput; } }
KnockKnockServer.java
import java.net.*; import java.io.*; public class KnockKnockServer { public static void main(String[] args) throws IOException { if (args.length != 1) { System.err.println("Usage: java KnockKnockServer <port number>"); System.exit(1); } int portNumber = Integer.parseInt(args[0]); try ( ServerSocket serverSocket = new ServerSocket(portNumber); Socket clientSocket = serverSocket.accept(); PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true); BufferedReader in = new BufferedReader( new InputStreamReader(clientSocket.getInputStream())); ) { String inputLine, outputLine; // Initiate conversation with client KnockKnockProtocol kkp = new KnockKnockProtocol(); outputLine = kkp.processInput(null); out.println(outputLine); while ((inputLine = in.readLine()) != null) { outputLine = kkp.processInput(inputLine); out.println(outputLine); if (outputLine.equals("Bye.")) break; } } catch (IOException e) { System.out.println("Exception caught when trying to listen on port " + portNumber + " or listening for a connection"); System.out.println(e.getMessage()); } } }
Maintained by John Loomis, updated Sun Apr 09 19:20:56 2017