client.java

jdk-6u10-docs java开发宝典

/*
 * Copyright 2004 Sun Microsystems, Inc. All  Rights Reserved.
 *  
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
 * 
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 *  notice, this list of conditions and the following disclaimer.
 * 
 * -Redistribution in binary form must reproduce the above copyright 
 *  notice, this list of conditions and the following disclaimer in 
 *  the documentation and/or other materials provided with the 
 *  distribution.
 *  
 * Neither the name of Sun Microsystems, Inc. or the names of 
 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
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 */
package example.inetd;

import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;

/**
 * A client that looks up a service by name in a registry on the port,
 * supplied as a command-line argument, and invokes a method on the
 * service.
 *
 * <p>The service may be configured to be launched by <code>inetd</code> so 
 * executing this client may start the service running.
 */
public class Client {

    public static void main(String[] args) throws Exception {

	int port = 0;
	String host = "";
	String message = "";
	
	/*
	 * Parse port argument.
	 */
	if (args.length > 2) {
	    host = args[0];
	    
	    try {
		port = Integer.parseInt(args[1]);
		if (port == 0) {
		    goodbye("nonzero port argument required", null);
		}
		
	    } catch (NumberFormatException e) {
		goodbye("malformed port argument", e);

	    }
	    message = args[2];
	    
	} else {
	    usage();
	}

	/*
	 * Lookup service by name in the registry on the specified host and 
	 * port.
	 */
	Registry registry = LocateRegistry.getRegistry(host, port);
	ServiceInterface proxy =
	    (ServiceInterface) registry.lookup("ServiceInterface");

	/*
	 * Invoke the 'sendMessage' method on the service passing the
	 * specified message.
	 */
	System.out.println("sending message: " + message);
	System.out.println("received message from proxy: " +
			   proxy.sendMessage(message));
	
	System.out.println("done.");
    }

    /**
     * Prints message and exception (if any), then exits.
     */
    private static void goodbye(String message, Exception e) {
	System.err.println("Client: " + message + (e != null ? ": " : ""));
	if (e != null) {
	    e.printStackTrace();
	}
	System.exit(1);
    }

    /**
     * Prints usage message, then exits.
     */
    private static void usage() {
	System.err.println("Client <host> <port> <message>");
	System.exit(1);
    }
}