Java 1.2 How-To/JavaHowTo.iso/3rdParty/jbuilder/unsupported/JDK1.2beta3/SOURCE/SRC.ZIP/java/rmi/Naming.java

Java Source | 1998-03-20 | 4.9 KB | 184 lines

/*
 * @(#)Naming.java    1.6 98/03/18
 *
 * Copyright 1996, 1997 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */
package java.rmi;

import java.rmi.registry.*;
import java.net.URL;
import java.net.MalformedURLException;

/**
 * This is the bootstrap mechanism for obtaining references to remote
 * objects based on Uniform Resource Locator (URL) syntax.  The URL
 * for a remote object is specified using the usual host, port and
 * name:
 *<br>    rmi://host:port/name
 *<br>    host = host name of registry  (defaults to current host)
 *<br>    port = port number of registry (defaults to the registry port number)
 *<br>  name = name for remote object
 */
public final class Naming {
    /*
     * Disallow anyone from creating one of these
     */
    private Naming() {}

    /**
     * Returns the remote object for the URL.
     * @exception RemoteException If registry could not be contacted.
     * @exception NotBoundException If name is not currently bound.
     */
    public static Remote lookup(String name)
    throws NotBoundException,
        java.net.MalformedURLException,
        UnknownHostException,
        RemoteException
    {
    URL url = cleanURL(name);
    Registry registry = getRegistry(url);

    String file = getName(url);
    if (file == null)
        return registry;
    return registry.lookup(file);
    }

    /**
     * Binds the name to the specified remote object.
     * @exception RemoteException If registry could not be contacted.
     * @exception AlreadyBoundException If name is already bound.
     */
    public static void bind(String name, Remote obj)
    throws AlreadyBoundException,
        java.net.MalformedURLException,
        UnknownHostException,
        RemoteException
    {
    URL url = cleanURL(name);
    Registry registry = getRegistry(url);

    if (obj == null)
        throw new NullPointerException("cannot bind to null");

    registry.bind(getName(url), obj);
    }

    /**
     * Unbind the name.
     * @exception RemoteException If registry could not be contacted.
     * @exception NotBoundException If name is not currently bound.
     */
    public static void unbind(String name)
    throws RemoteException,
        NotBoundException,
        java.net.MalformedURLException,
        UnknownHostException
    {
    URL url = cleanURL(name);
    Registry registry = getRegistry(url);

    registry.unbind(getName(url));
    }

    /**
     * Rebind the name to a new object; replaces any existing binding.
     * @exception RemoteException If registry could not be contacted.
     */
    public static void rebind(String name, Remote obj)
    throws RemoteException,
        java.net.MalformedURLException,
        UnknownHostException
    {
    URL url = cleanURL(name);
    Registry registry = getRegistry(url);

    if (obj == null)
        throw new NullPointerException("cannot bind to null");

    registry.rebind(getName(url), obj);
    }

    /**
     * Returns an array of strings of the URLs in the registry.
     * The array contains a snapshot of the names present in the registry.
     * @exception RemoteException If registry could not be contacted.
     */
    public static String[] list(String name)
    throws RemoteException,
        java.net.MalformedURLException,
        UnknownHostException
    {
    URL url = cleanURL(name);
    Registry registry = getRegistry(url);

    String host = url.getHost();
    int port = url.getPort();

    String prefix = "rmi:";
     if (port > 0 || !host.equals(""))
        prefix += "//" + host;
    if (port > 0)
        prefix += ":" + port;
    prefix += "/";

    String[] names = registry.list();
    for (int i = 0; i < names.length; i++) {
        names[i] = prefix + names[i];
    }
    return names;
    }

    /** Function to find registry from URL
     */
    private static Registry getRegistry(URL url)
    throws RemoteException, UnknownHostException
    {
    String host = url.getHost();
    int port = url.getPort();

    return LocateRegistry.getRegistry(host, port);
    }

    /** Function to extract only the name from the URL.
     */
    private static String getName(URL url)
    {
    String name = url.getFile();
    if (name == null || name.equals("/"))
        return null;
    return name.substring(1);
    }

    /**
     * Function to cleanup and create the URL.
     * It checks for and removes the protocol
     */
    private static URL cleanURL(String name)
    throws java.net.MalformedURLException
    {
    URL url = new URL("file:");

    // remove the approved protocol
    if (name.startsWith("rmi:"))
        name = name.substring(4);

    // No protocol must remain
    int colon = name.indexOf(':');
    if (colon >= 0 && colon < name.indexOf('/') )
        throw new java.net.MalformedURLException("Protocol should be rmi:");

    url = new URL(url, name);
    return url;
    }
}