001 /* MarshalledObject.java --
002 Copyright (c) 1996, 1997, 1998, 1999, 2004, 2006
003 Free Software Foundation, Inc.
004
005 This file is part of GNU Classpath.
006
007 GNU Classpath is free software; you can redistribute it and/or modify
008 it under the terms of the GNU General Public License as published by
009 the Free Software Foundation; either version 2, or (at your option)
010 any later version.
011
012 GNU Classpath is distributed in the hope that it will be useful, but
013 WITHOUT ANY WARRANTY; without even the implied warranty of
014 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 General Public License for more details.
016
017 You should have received a copy of the GNU General Public License
018 along with GNU Classpath; see the file COPYING. If not, write to the
019 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020 02110-1301 USA.
021
022 Linking this library statically or dynamically with other modules is
023 making a combined work based on this library. Thus, the terms and
024 conditions of the GNU General Public License cover the whole
025 combination.
026
027 As a special exception, the copyright holders of this library give you
028 permission to link this library with independent modules to produce an
029 executable, regardless of the license terms of these independent
030 modules, and to copy and distribute the resulting executable under
031 terms of your choice, provided that you also meet, for each linked
032 independent module, the terms and conditions of the license of that
033 module. An independent module is a module which is not derived from
034 or based on this library. If you modify this library, you may extend
035 this exception to your version of the library, but you are not
036 obligated to do so. If you do not wish to do so, delete this
037 exception statement from your version. */
038
039
040 package java.rmi;
041
042 import gnu.java.rmi.RMIMarshalledObjectInputStream;
043 import gnu.java.rmi.RMIMarshalledObjectOutputStream;
044
045 import java.io.ByteArrayOutputStream;
046 import java.io.IOException;
047 import java.io.Serializable;
048
049 /**
050 * A <code>MarshalledObject</code> consists of a serialized object which is
051 * marshalled according to the RMI specification.
052 * <p>
053 * An object passed to the constructor is serialized and tagged with the needed
054 * URL to retrieve its class definition for remote usage. If the object is a
055 * remote reference its stub is serialized instead. The instance of this
056 * marshalled object can be later retrieved by its <code>get()</code> method.
057 * </p>
058 *
059 * @author unknown
060 */
061 public final class MarshalledObject<T>
062 implements Serializable
063 {
064 // The following fields are from Java API Documentation "Serialized form"
065 private static final long serialVersionUID = 8988374069173025854L;
066
067 byte[] objBytes;
068 byte[] locBytes;
069 int hash;
070
071 /**
072 * Constructs a <code>MarshalledObject</code> from the given object.
073 *
074 * @param obj the object to marshal
075 * @throws IOException if an I/O error during serialization occurs.
076 */
077 public MarshalledObject(T obj) throws IOException
078 {
079 ByteArrayOutputStream objStream = new ByteArrayOutputStream();
080 RMIMarshalledObjectOutputStream stream =
081 new RMIMarshalledObjectOutputStream(objStream);
082 stream.writeObject(obj);
083 stream.flush();
084 objBytes = objStream.toByteArray();
085 locBytes = stream.getLocBytes();
086
087 // The following algorithm of calculating hashCode is similar to String
088 hash = 0;
089 for (int i = 0; i < objBytes.length; i++)
090 hash = hash * 31 + objBytes[i];
091
092 if (locBytes != null)
093 for (int i = 0; i < locBytes.length; i++)
094 hash = hash * 31 + locBytes[i];
095 }
096
097 /**
098 * Checks if the given object is equal to this marshalled object.
099 *
100 * <p>Marshalled objects are considered equal if they contain the
101 * same serialized object. Codebase annotations where the class
102 * definition can be downloaded are ignored in the equals test.</p>
103 *
104 * @param obj the object to compare.
105 * @return <code>true</code> if equal, <code>false</code> otherwise.
106 */
107 public boolean equals(Object obj)
108 {
109 if (! (obj instanceof MarshalledObject))
110 return false;
111
112 // hashCode even differs, don't do the time-consuming comparisons
113 if (obj.hashCode() != hash)
114 return false;
115
116 MarshalledObject aobj = (MarshalledObject) obj;
117 if (objBytes == null || aobj.objBytes == null)
118 return objBytes == aobj.objBytes;
119 if (objBytes.length != aobj.objBytes.length)
120 return false;
121 for (int i = 0; i < objBytes.length; i++)
122 {
123 if (objBytes[i] != aobj.objBytes[i])
124 return false;
125 }
126 // Ignore comparison of locBytes(annotation)
127 return true;
128 }
129
130 /**
131 * Constructs and returns a copy of the internal serialized object.
132 *
133 * @return The deserialized object.
134 *
135 * @throws IOException if an I/O exception occurs during deserialization.
136 * @throws ClassNotFoundException if the class of the deserialized object
137 * cannot be found.
138 */
139 public T get() throws IOException, ClassNotFoundException
140 {
141 if (objBytes == null)
142 return null;
143
144 RMIMarshalledObjectInputStream stream =
145 new RMIMarshalledObjectInputStream(objBytes, locBytes);
146 return (T) stream.readObject();
147 }
148
149 public int hashCode()
150 {
151 return hash;
152 }
153
154 }