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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: */ 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: */ 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: }