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 }