java_rmi.rar_RMI java_java.rmi

/* * 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);