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 }