001 /* RemoteObject.java --
002 Copyright (c) 1996, 1997, 1998, 1999, 2004 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.rmi.server;
039
040 import java.io.IOException;
041 import java.io.ObjectInputStream;
042 import java.io.ObjectOutput;
043 import java.io.ObjectOutputStream;
044 import java.io.Serializable;
045 import java.rmi.NoSuchObjectException;
046 import java.rmi.Remote;
047 import java.rmi.UnmarshalException;
048 import java.util.WeakHashMap;
049
050 public abstract class RemoteObject
051 implements Remote, Serializable {
052
053 private static final long serialVersionUID = -3215090123894869218l;
054
055 protected transient RemoteRef ref;
056
057 private static final WeakHashMap stubs = new WeakHashMap();
058
059 protected RemoteObject() {
060 this(null);
061 }
062
063 protected RemoteObject(RemoteRef newref) {
064 ref = newref;
065 }
066
067 public RemoteRef getRef() {
068 return (ref);
069 }
070
071 synchronized static void addStub(Remote obj, Remote stub)
072 {
073 stubs.put(obj, stub);
074 }
075
076 synchronized 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
091 public int hashCode() {
092 if (ref == null) {
093 return (0);
094 }
095 else {
096 return (ref.hashCode());
097 }
098 }
099
100 public 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 }