001/* MarshalledObject.java -- 002 Copyright (c) 1996, 1997, 1998, 1999, 2004, 2006 003 Free Software Foundation, Inc. 004 005This file is part of GNU Classpath. 006 007GNU Classpath is free software; you can redistribute it and/or modify 008it under the terms of the GNU General Public License as published by 009the Free Software Foundation; either version 2, or (at your option) 010any later version. 011 012GNU Classpath is distributed in the hope that it will be useful, but 013WITHOUT ANY WARRANTY; without even the implied warranty of 014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 015General Public License for more details. 016 017You should have received a copy of the GNU General Public License 018along with GNU Classpath; see the file COPYING. If not, write to the 019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02002110-1301 USA. 021 022Linking this library statically or dynamically with other modules is 023making a combined work based on this library. Thus, the terms and 024conditions of the GNU General Public License cover the whole 025combination. 026 027As a special exception, the copyright holders of this library give you 028permission to link this library with independent modules to produce an 029executable, regardless of the license terms of these independent 030modules, and to copy and distribute the resulting executable under 031terms of your choice, provided that you also meet, for each linked 032independent module, the terms and conditions of the license of that 033module. An independent module is a module which is not derived from 034or based on this library. If you modify this library, you may extend 035this exception to your version of the library, but you are not 036obligated to do so. If you do not wish to do so, delete this 037exception statement from your version. */ 038 039 040package java.rmi; 041 042import gnu.java.rmi.RMIMarshalledObjectInputStream; 043import gnu.java.rmi.RMIMarshalledObjectOutputStream; 044 045import java.io.ByteArrayOutputStream; 046import java.io.IOException; 047import 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 */ 061public 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}