001/* RemoteObject.java --
002   Copyright (c) 1996, 1997, 1998, 1999, 2004  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.rmi.server;
039
040import java.io.IOException;
041import java.io.ObjectInputStream;
042import java.io.ObjectOutput;
043import java.io.ObjectOutputStream;
044import java.io.Serializable;
045import java.rmi.NoSuchObjectException;
046import java.rmi.Remote;
047import java.rmi.UnmarshalException;
048import java.util.WeakHashMap;
049
050public abstract class RemoteObject
051        implements Remote, Serializable {
052
053private static final long serialVersionUID = -3215090123894869218l;
054
055protected transient RemoteRef ref;
056
057private static final WeakHashMap stubs = new WeakHashMap();
058
059protected RemoteObject() {
060        this(null);
061}
062
063protected RemoteObject(RemoteRef newref) {
064        ref = newref;
065}
066
067public RemoteRef getRef() {
068        return (ref);
069}
070
071synchronized static void addStub(Remote obj, Remote stub)
072{
073  stubs.put(obj, stub);
074}
075
076synchronized static void deleteStub(Remote obj)
077{
078  stubs.remove(obj);
079}
080
081  public static Remote toStub(Remote obj) throws NoSuchObjectException
082  {
083    Remote stub = (Remote)stubs.get(obj);
084
085    if (stub == null)
086      throw new NoSuchObjectException(obj.getClass().getName());
087
088    return stub;
089  }
090
091public int hashCode() {
092        if (ref == null) {
093                return (0);
094        }
095        else {
096                return (ref.hashCode());
097        }
098}
099
100public boolean equals(Object obj) {
101        // We only compare references.
102        return (this == obj);
103}
104
105/**
106 * Get the string representation of this remote object.
107 */
108  public String toString()
109  {
110    if (ref == null)
111      return getClass ().toString ();
112    return (ref.toString ());
113  }
114
115  /**
116   * Read the remote object from the input stream. Expects the class name
117   * without package first. Then the method creates and assigns the {@link #ref}
118   * an instance of this class and calls its .readExternal method. The standard
119   * packageless class names are UnicastRef, UnicastRef2, UnicastServerRef,
120   * UnicastServerRef2, ActivatableRef or ActivatableServerRef.
121   *
122   * @param in the stream to read from
123   * @throws IOException if the IO exception occurs
124   * @throws ClassNotFoundException if the class with the given name is not
125   *           present in the package gnu.java.rmi.server (for the case of the
126   *           GNU Classpath.
127   */
128  private void readObject(ObjectInputStream in) throws IOException,
129      ClassNotFoundException
130  {
131    String cname = in.readUTF();
132    if (! cname.equals(""))
133      {
134        if (cname.equals("UnicastRef2"))
135          {
136            // hack for interoperating with JDK
137            cname = "UnicastRef";
138            in.read(); // some unknown UnicastRef2 field
139          }
140
141        // It would be nice to use RemoteRef.packagePrefix here, but for binary
142        // compatibility with the JDK that has to contain "sun.rmi.server"...
143        cname = "gnu.java.rmi.server." + cname;
144        try
145          {
146            Class cls = Class.forName(cname);
147            ref = (RemoteRef) cls.newInstance();
148          }
149        catch (InstantiationException e1)
150          {
151            throw new UnmarshalException("failed to create ref", e1);
152          }
153        catch (IllegalAccessException e2)
154          {
155            throw new UnmarshalException("failed to create ref", e2);
156          }
157        ref.readExternal(in);
158      }
159    else
160      {
161        ref = (RemoteRef) in.readObject();
162      }
163  }
164
165  /**
166   * Write the remote object to the output stream. This method first calls
167   * {@link RemoteRef#getRefClass(ObjectOutput)} on the {@link #ref} to get the
168   * class name without package, writes this name and then calls the
169   * ref.writeObject to write the data. The standard packageless class names are
170   * UnicastRef, UnicastRef2, UnicastServerRef, UnicastServerRef2,
171   * ActivatableRef or ActivatableServerRef. The empty string with the
172   * subsequently following serialized ref instance be written if the
173   * ref.getRefClass returns null.
174   *
175   * @param out the stream to write to
176   * @throws IOException if one occurs during writing
177   * @throws ClassNotFoundException never in this implementation (specified as
178   *           part of the API standard)
179   * @throws UnmarshalException if the remote reference of this remote object is
180   *           null.
181   */
182  private void writeObject(ObjectOutputStream out) throws IOException,
183      ClassNotFoundException
184  {
185    if (ref == null)
186      {
187        throw new UnmarshalException("no ref to serialize");
188      }
189    String cname = ref.getRefClass(out);
190    if (cname != null && cname.length() > 0)
191      {
192        out.writeUTF(cname);
193        ref.writeExternal(out);
194      }
195    else
196      {
197        out.writeUTF("");
198        out.writeObject(ref);
199      }
200  }
201
202}