1 /* RemoteObjectInvocationHandler.java -- RMI stub replacement. 2 Copyright (C) 2005 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package java.rmi.server; 40 41 import gnu.java.rmi.server.RMIHashes; 42 43 import java.io.Serializable; 44 import java.lang.reflect.InvocationHandler; 45 import java.lang.reflect.Method; 46 import java.lang.reflect.Proxy; 47 import java.rmi.Remote; 48 import java.rmi.RemoteException; 49 import java.rmi.UnexpectedException; 50 import java.rmi.registry.Registry; 51 import java.rmi.server.RemoteObject; 52 import java.rmi.server.RemoteRef; 53 import java.rmi.server.UnicastRemoteObject; 54 import java.util.Hashtable; 55 56 /** 57 * Together with dynamic proxy instance, this class replaces the generated RMI 58 * stub (*_Stub) classes that (following 1.5 specification) should be no longer 59 * required. It is unusual to use the instances of this class directly in the 60 * user program. Such instances are automatically created and returned by 61 * {@link Registry} or {@link UnicastRemoteObject} methods if the remote 62 * reference is known but the corresponding stub class is not accessible. 63 * 64 * @see Registry#lookup 65 * 66 * @author Audrius Meskauskas (AudriusA@Bioinformatics.org) 67 */ 68 public class RemoteObjectInvocationHandler extends RemoteObject implements 69 InvocationHandler, Remote, Serializable 70 { 71 /** 72 * Use the jdk 1.5 SUID for interoperability. 73 */ 74 static final long serialVersionUID = 2L; 75 76 /** 77 * The RMI method hash codes, computed once as described in the section 8.3 78 * of the Java Remote Method Invocation (RMI) Specification. 79 */ 80 static Hashtable methodHashCodes = new Hashtable(); 81 82 /** 83 * The empty class array to define parameters of .hashCode and .toString. 84 */ 85 static final Class[] noArgsC = new Class[0]; 86 87 /** 88 * The class array to define parameters of .equals 89 */ 90 static final Class[] anObjectC = new Class[] { Object.class }; 91 92 /** 93 * The empty object array to replace null when no args are passed. 94 */ 95 static final Object[] noArgs = new Object[0]; 96 97 /** 98 * Construct the remote invocation handler that forwards calls to the given 99 * remote object. 100 * 101 * @param reference the reference to the remote object where the method 102 * calls should be forwarded. 103 */ RemoteObjectInvocationHandler(RemoteRef reference)104 public RemoteObjectInvocationHandler(RemoteRef reference) 105 { 106 super(reference); 107 } 108 109 /** 110 * Invoke the remote method. When the known method is invoked on a created RMI 111 * stub proxy class, the call is delivered to this method and then transferred 112 * to the {@link RemoteRef#invoke(Remote, Method, Object[], long)} of the 113 * remote reference that was passed in constructor. The methods are handled as 114 * following: 115 * <ul> 116 * <li> The toString() method is delegated to the passed proxy instance.</li> 117 * <li>The .equals method only returns true if the passed object is an 118 * instance of proxy class and its invocation handler is equal to this 119 * invocation handles.</li> 120 * <li>The .hashCode returns the hashCode of this invocation handler (if the.</li> 121 * <li>All other methods are converted to remote calls and forwarded to the 122 * remote reference. </li> 123 * </ul> 124 * 125 * @param proxyInstance 126 * the instance of the proxy stub 127 * @param method 128 * the method being invoked 129 * @param parameters 130 * the method parameters 131 * @return the method return value, returned by RemoteRef.invoke 132 * @throws IllegalAccessException 133 * if the passed proxy instance does not implement Remote interface. 134 * @throws UnexpectedException 135 * if remote call throws some exception, not listed in the 136 * <code>throws</code> clause of the method being called. 137 * @throws Throwable 138 * that is thrown by remote call, if that exception is listend in 139 * the <code>throws</code> clause of the method being called. 140 */ invoke(Object proxyInstance, Method method, Object[] parameters)141 public Object invoke(Object proxyInstance, Method method, Object[] parameters) 142 throws Throwable 143 { 144 if (!(proxyInstance instanceof Remote)) 145 { 146 String name = proxyInstance == null ? "null" 147 : proxyInstance.getClass().getName(); 148 throw new IllegalAccessException(name + " does not implement " 149 + Remote.class.getName()); 150 } 151 152 if (parameters == null) 153 parameters = noArgs; 154 155 String name = method.getName(); 156 switch (name.charAt(0)) 157 { 158 case 'e': 159 if (parameters.length == 1 && name.equals("equals") 160 && method.getParameterTypes()[0].equals(Object.class)) 161 { 162 if (parameters[0] instanceof Proxy) 163 { 164 Object handler = Proxy.getInvocationHandler(parameters[0]); 165 if (handler == null) 166 return Boolean.FALSE; 167 else 168 return handler.equals(this) ? Boolean.TRUE : Boolean.FALSE; 169 } 170 else 171 return Boolean.FALSE; 172 } 173 break; 174 case 'h': 175 if (parameters.length == 0 && name.equals("hashCode")) 176 { 177 int hashC = Proxy.getInvocationHandler(proxyInstance).hashCode(); 178 return new Integer(hashC); 179 } 180 break; 181 case 't': 182 if (parameters.length == 0 && name.equals("toString")) 183 return "Proxy stub:"+ref.remoteToString(); 184 break; 185 default: 186 break; 187 } 188 189 Long hash = (Long) methodHashCodes.get(method); 190 if (hash == null) 191 { 192 hash = new Long(RMIHashes.getMethodHash(method)); 193 methodHashCodes.put(method, hash); 194 } 195 196 try 197 { 198 return getRef().invoke((Remote) proxyInstance, method, parameters, 199 hash.longValue()); 200 } 201 catch (RuntimeException exception) 202 { 203 // RuntimeException is always supported. 204 throw exception; 205 } 206 catch (RemoteException exception) 207 { 208 // All remote methods can throw RemoteException. 209 throw exception; 210 } 211 catch (Error exception) 212 { 213 throw exception; 214 } 215 catch (Exception exception) 216 { 217 Class[] exceptions = method.getExceptionTypes(); 218 Class exceptionClass = exception.getClass(); 219 220 for (int i = 0; i < exceptions.length; i++) 221 { 222 if (exceptions[i].equals(exceptionClass)) 223 throw exception; 224 } 225 throw new UnexpectedException(method.getName(), exception); 226 } 227 } 228 229 } 230