/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.rmi;import java.rmi.*;import java.rmi.server.*;import java.rmi.registry.*;import java.io.*;import java.util.*;import com.davidflanagan.examples.rmi.Mud.*;/** * This class is a client program for the MUD.  The main() method sets up  * a connection to a RemoteMudServer, gets the initial RemoteMudPlace object, * and creates a MudPerson object to represent the user in the MUD.  Then it  * calls runMud() to put the person in the place, begins processing * user commands.  The getLine() and getMultiLine() methods are convenience * methods used throughout to get input from the user. **/public class MudClient {    /**     * The main program.  It expects two or three arguments:     *   0) the name of the host on which the mud server is running     *   1) the name of the MUD on that host     *   2) the name of a place within that MUD to start at (optional).     *     * It uses the Naming.lookup() method to obtain a RemoteMudServer object     * for the named MUD on the specified host.  Then it uses the getEntrance()     * or getNamedPlace() method of RemoteMudServer to obtain the starting     * RemoteMudPlace object.  It prompts the user for a their name and      * description, and creates a MudPerson object.  Finally, it passes     * the person and the place to runMud() to begin interaction with the MUD.     **/    public static void main(String[] args) {        try {            String hostname = args[0]; // Each MUD is uniquely identified by a             String mudname = args[1];  //   host and a MUD name.            String placename = null;   // Each place in a MUD has a unique name            if (args.length > 2) placename = args[2];	                // Look up the RemoteMudServer object for the named MUD using            // the default registry on the specified host.  Note the use of            // the Mud.mudPrefix constant to help prevent naming conflicts            // in the registry.            RemoteMudServer server =                 (RemoteMudServer)Naming.lookup("rmi://" + hostname + "/" +					       Mud.mudPrefix + mudname);            // If the user did not specify a place in the mud, use            // getEntrance() to get the initial place.  Otherwise, call            // getNamedPlace() to find the initial place.            RemoteMudPlace location = null;            if (placename == null) location = server.getEntrance();            else location = (RemoteMudPlace) server.getNamedPlace(placename);	                // Greet the user and ask for their name and description.            // This relies on getLine() and getMultiLine() defined below.            System.out.println("Welcome to " + mudname);            String name = getLine("Enter your name: ");            String description = getMultiLine("Please describe what " +					  "people see when they look at you:");            // Define an output stream that the MudPerson object will use to            // display messages sent to it to the user.  We'll use the console.            PrintWriter myout = new PrintWriter(System.out);	                // Create a MudPerson object to represent the user in the MUD.            // Use the specified name and description, and the output stream.            MudPerson me = new MudPerson(name, description, myout);	                // Lower this thread's priority one notch so that broadcast            // messages can appear even when we're blocking for I/O.  This is            // necessary on the Linux platform, but may not be necessary on all            // platforms.            int pri = Thread.currentThread().getPriority();            Thread.currentThread().setPriority(pri-1);	                // Finally, put the MudPerson into the RemoteMudPlace, and start            // prompting the user for commands.            runMud(location, me);        }        // If anything goes wrong, print a message and exit.        catch (Exception e) {            System.out.println(e);            System.out.println("Usage: java MudClient <host> <mud> [<place>]");            System.exit(1);        }    }    /**     * This method is the main loop of the MudClient.  It places the person     * into the place (using the enter() method of RemoteMudPlace).  Then it     * calls the look() method to describe the place to the user, and enters a     * command loop to prompt the user for a command and process the command     **/    public static void runMud(RemoteMudPlace entrance, MudPerson me) 	throws RemoteException    {        RemoteMudPlace location = entrance;  // The current place        String myname = me.getName();        // The person's name        String placename = null;             // The name of the current place        String mudname = null;             // The name of the mud of that place        try {             // Enter the MUD            location.enter(me, myname, myname + " has entered the MUD.");             // Figure out where we are (for the prompt)            mudname = location.getServer().getMudName();            placename = location.getPlaceName();            // Describe the place to the user            look(location);        }        catch (Exception e) {            System.out.println(e);            System.exit(1);        }	        // Now that we've entered the MUD, begin a command loop to process        // the user's commands.  Note that there is a huge block of catch        // statements at the bottom of the loop to handle all the things that        // could go wrong each time through the loop.        for(;;) {  // Loop until the user types "quit"            try {    // Catch any exceptions that occur in the loop                // Pause just a bit before printing the prompt, to give output                // generated indirectly by the last command a chance to appear.                try { Thread.sleep(200); } catch (InterruptedException e) {}                // Display a prompt, and get the user's input                String line = getLine(mudname + '.' + placename + "> ");		                // Break the input into a command and an argument that consists                // of the rest of the line.  Convert the command to lowercase.                String cmd, arg;                int i = line.indexOf(' ');                if (i == -1) { cmd = line; arg = null; }                else {                    cmd = line.substring(0, i).toLowerCase();                    arg = line.substring(i+1);                }                if (arg == null) arg = "";		                // Now go process the command.  What follows is a huge repeated                // if/else statement covering each of the commands supported by                // this client.  Many of these commands simply invoke one of                // the remote methods of the current RemoteMudPlace object.                // Some have to do a bit of additional processing.                // LOOK: Describe the place and its things, people, and exits                if (cmd.equals("look")) look(location);                // EXAMINE: Describe a named thing                else if (cmd.equals("examine"))                     System.out.println(location.examineThing(arg));                // DESCRIBE: Describe a named person                else if (cmd.equals("describe")) {                    try {                         RemoteMudPerson p = location.getPerson(arg);                        System.out.println(p.getDescription());                     }                    catch(RemoteException e) {                        System.out.println(arg + " is having technical " +					   "difficulties. No description " +					   "is available.");                    }                }                // GO: Go in a named direction                else if (cmd.equals("go")) {                    location = location.go(me, arg);                    mudname = location.getServer().getMudName();                    placename = location.getPlaceName();                    look(location);                }                // SAY: Say something to everyone                 else if (cmd.equals("say")) location.speak(me, arg);                // DO: Do something that will be described to everyone                else if (cmd.equals("do")) location.act(me, arg);                // TALK: Say something to one named person                else if (cmd.equals("talk")) {                    try {                        RemoteMudPerson p = location.getPerson(arg);                        String msg = getLine("What do you want to say?: ");                        p.tell(myname + " says \"" + msg + "\"");                    }                    catch (RemoteException e) {                        System.out.println(arg + " is having technical " +			   	         "difficulties. Can't talk to them.");                    }                }                // CHANGE: Change my own description                 else if (cmd.equals("change"))                    me.setDescription(			    getMultiLine("Describe yourself for others: "));                // CREATE: Create a new thing in this place                else if (cmd.equals("create")) {                    if (arg.length() == 0)                        throw new IllegalArgumentException("name expected");                    String desc = getMultiLine("Please describe the " +					       arg + ": ");                    location.createThing(me, arg, desc);                }                // DESTROY: Destroy a named thing                else if (cmd.equals("destroy")) location.destroyThing(me, arg);                // OPEN: Create a new place and connect this place to it                // through the exit specified in the argument.                else if (cmd.equals("open")) {                    if (arg.length() == 0)                       throw new IllegalArgumentException("direction expected");                    String name = getLine("What is the name of place there?: ");                    String back = getLine("What is the direction from " + 					  "there back to here?: ");                    String desc = getMultiLine("Please describe " +