J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | package java.rmi.server; |
| 26 | |
| 27 | import java.io.InvalidObjectException; |
| 28 | import java.lang.reflect.InvocationHandler; |
| 29 | import java.lang.reflect.Method; |
| 30 | import java.lang.reflect.Proxy; |
| 31 | import java.rmi.Remote; |
| 32 | import java.rmi.UnexpectedException; |
| 33 | import java.rmi.activation.Activatable; |
| 34 | import java.util.Map; |
| 35 | import java.util.WeakHashMap; |
| 36 | import sun.rmi.server.Util; |
| 37 | import sun.rmi.server.WeakClassHashMap; |
| 38 | |
| 39 | /** |
| 40 | * An implementation of the <code>InvocationHandler</code> interface for |
| 41 | * use with Java Remote Method Invocation (Java RMI). This invocation |
| 42 | * handler can be used in conjunction with a dynamic proxy instance as a |
| 43 | * replacement for a pregenerated stub class. |
| 44 | * |
| 45 | * <p>Applications are not expected to use this class directly. A remote |
| 46 | * object exported to use a dynamic proxy with {@link UnicastRemoteObject} |
| 47 | * or {@link Activatable} has an instance of this class as that proxy's |
| 48 | * invocation handler. |
| 49 | * |
| 50 | * @author Ann Wollrath |
| 51 | * @since 1.5 |
| 52 | **/ |
| 53 | public class RemoteObjectInvocationHandler |
| 54 | extends RemoteObject |
| 55 | implements InvocationHandler |
| 56 | { |
| 57 | private static final long serialVersionUID = 2L; |
| 58 | |
| 59 | /** |
| 60 | * A weak hash map, mapping classes to weak hash maps that map |
| 61 | * method objects to method hashes. |
| 62 | **/ |
| 63 | private static final MethodToHash_Maps methodToHash_Maps = |
| 64 | new MethodToHash_Maps(); |
| 65 | |
| 66 | /** |
| 67 | * Creates a new <code>RemoteObjectInvocationHandler</code> constructed |
| 68 | * with the specified <code>RemoteRef</code>. |
| 69 | * |
| 70 | * @param ref the remote ref |
| 71 | * |
| 72 | * @throws NullPointerException if <code>ref</code> is <code>null</code> |
| 73 | **/ |
| 74 | public RemoteObjectInvocationHandler(RemoteRef ref) { |
| 75 | super(ref); |
| 76 | if (ref == null) { |
| 77 | throw new NullPointerException(); |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | /** |
| 82 | * Processes a method invocation made on the encapsulating |
| 83 | * proxy instance, <code>proxy</code>, and returns the result. |
| 84 | * |
| 85 | * <p><code>RemoteObjectInvocationHandler</code> implements this method |
| 86 | * as follows: |
| 87 | * |
| 88 | * <p>If <code>method</code> is one of the following methods, it |
| 89 | * is processed as described below: |
| 90 | * |
| 91 | * <ul> |
| 92 | * |
| 93 | * <li>{@link Object#hashCode Object.hashCode}: Returns the hash |
| 94 | * code value for the proxy. |
| 95 | * |
| 96 | * <li>{@link Object#equals Object.equals}: Returns <code>true</code> |
| 97 | * if the argument (<code>args[0]</code>) is an instance of a dynamic |
| 98 | * proxy class and this invocation handler is equal to the invocation |
| 99 | * handler of that argument, and returns <code>false</code> otherwise. |
| 100 | * |
| 101 | * <li>{@link Object#toString Object.toString}: Returns a string |
| 102 | * representation of the proxy. |
| 103 | * </ul> |
| 104 | * |
| 105 | * <p>Otherwise, a remote call is made as follows: |
| 106 | * |
| 107 | * <ul> |
| 108 | * <li>If <code>proxy</code> is not an instance of the interface |
| 109 | * {@link Remote}, then an {@link IllegalArgumentException} is thrown. |
| 110 | * |
| 111 | * <li>Otherwise, the {@link RemoteRef#invoke invoke} method is invoked |
| 112 | * on this invocation handler's <code>RemoteRef</code>, passing |
| 113 | * <code>proxy</code>, <code>method</code>, <code>args</code>, and the |
| 114 | * method hash (defined in section 8.3 of the "Java Remote Method |
| 115 | * Invocation (RMI) Specification") for <code>method</code>, and the |
| 116 | * result is returned. |
| 117 | * |
| 118 | * <li>If an exception is thrown by <code>RemoteRef.invoke</code> and |
| 119 | * that exception is a checked exception that is not assignable to any |
| 120 | * exception in the <code>throws</code> clause of the method |
| 121 | * implemented by the <code>proxy</code>'s class, then that exception |
| 122 | * is wrapped in an {@link UnexpectedException} and the wrapped |
| 123 | * exception is thrown. Otherwise, the exception thrown by |
| 124 | * <code>invoke</code> is thrown by this method. |
| 125 | * </ul> |
| 126 | * |
| 127 | * <p>The semantics of this method are unspecified if the |
| 128 | * arguments could not have been produced by an instance of some |
| 129 | * valid dynamic proxy class containing this invocation handler. |
| 130 | * |
| 131 | * @param proxy the proxy instance that the method was invoked on |
| 132 | * @param method the <code>Method</code> instance corresponding to the |
| 133 | * interface method invoked on the proxy instance |
| 134 | * @param args an array of objects containing the values of the |
| 135 | * arguments passed in the method invocation on the proxy instance, or |
| 136 | * <code>null</code> if the method takes no arguments |
| 137 | * @return the value to return from the method invocation on the proxy |
| 138 | * instance |
| 139 | * @throws Throwable the exception to throw from the method invocation |
| 140 | * on the proxy instance |
| 141 | * @see |
| 142 | **/ |
| 143 | public Object invoke(Object proxy, Method method, Object[] args) |
| 144 | throws Throwable |
| 145 | { |
| 146 | if (method.getDeclaringClass() == Object.class) { |
| 147 | return invokeObjectMethod(proxy, method, args); |
| 148 | } else { |
| 149 | return invokeRemoteMethod(proxy, method, args); |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | /** |
| 154 | * Handles java.lang.Object methods. |
| 155 | **/ |
| 156 | private Object invokeObjectMethod(Object proxy, |
| 157 | Method method, |
| 158 | Object[] args) |
| 159 | { |
| 160 | String name = method.getName(); |
| 161 | |
| 162 | if (name.equals("hashCode")) { |
| 163 | return hashCode(); |
| 164 | |
| 165 | } else if (name.equals("equals")) { |
| 166 | Object obj = args[0]; |
| 167 | return |
| 168 | proxy == obj || |
| 169 | (obj != null && |
| 170 | Proxy.isProxyClass(obj.getClass()) && |
| 171 | equals(Proxy.getInvocationHandler(obj))); |
| 172 | |
| 173 | } else if (name.equals("toString")) { |
| 174 | return proxyToString(proxy); |
| 175 | |
| 176 | } else { |
| 177 | throw new IllegalArgumentException( |
| 178 | "unexpected Object method: " + method); |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | /** |
| 183 | * Handles remote methods. |
| 184 | **/ |
| 185 | private Object invokeRemoteMethod(Object proxy, |
| 186 | Method method, |
| 187 | Object[] args) |
| 188 | throws Exception |
| 189 | { |
| 190 | try { |
| 191 | if (!(proxy instanceof Remote)) { |
| 192 | throw new IllegalArgumentException( |
| 193 | "proxy not Remote instance"); |
| 194 | } |
| 195 | return ref.invoke((Remote) proxy, method, args, |
| 196 | getMethodHash(method)); |
| 197 | } catch (Exception e) { |
| 198 | if (!(e instanceof RuntimeException)) { |
| 199 | Class<?> cl = proxy.getClass(); |
| 200 | try { |
| 201 | method = cl.getMethod(method.getName(), |
| 202 | method.getParameterTypes()); |
| 203 | } catch (NoSuchMethodException nsme) { |
| 204 | throw (IllegalArgumentException) |
| 205 | new IllegalArgumentException().initCause(nsme); |
| 206 | } |
| 207 | Class<?> thrownType = e.getClass(); |
| 208 | for (Class<?> declaredType : method.getExceptionTypes()) { |
| 209 | if (declaredType.isAssignableFrom(thrownType)) { |
| 210 | throw e; |
| 211 | } |
| 212 | } |
| 213 | e = new UnexpectedException("unexpected exception", e); |
| 214 | } |
| 215 | throw e; |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | * Returns a string representation for a proxy that uses this invocation |
| 221 | * handler. |
| 222 | **/ |
| 223 | private String proxyToString(Object proxy) { |
| 224 | Class<?>[] interfaces = proxy.getClass().getInterfaces(); |
| 225 | if (interfaces.length == 0) { |
| 226 | return "Proxy[" + this + "]"; |
| 227 | } |
| 228 | String iface = interfaces[0].getName(); |
| 229 | if (iface.equals("java.rmi.Remote") && interfaces.length > 1) { |
| 230 | iface = interfaces[1].getName(); |
| 231 | } |
| 232 | int dot = iface.lastIndexOf('.'); |
| 233 | if (dot >= 0) { |
| 234 | iface = iface.substring(dot + 1); |
| 235 | } |
| 236 | return "Proxy[" + iface + "," + this + "]"; |
| 237 | } |
| 238 | |
| 239 | /** |
| 240 | * @throws InvalidObjectException unconditionally |
| 241 | **/ |
| 242 | private void readObjectNoData() throws InvalidObjectException { |
| 243 | throw new InvalidObjectException("no data in stream; class: " + |
| 244 | this.getClass().getName()); |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * Returns the method hash for the specified method. Subsequent calls |
| 249 | * to "getMethodHash" passing the same method argument should be faster |
| 250 | * since this method caches internally the result of the method to |
| 251 | * method hash mapping. The method hash is calculated using the |
| 252 | * "computeMethodHash" method. |
| 253 | * |
| 254 | * @param method the remote method |
| 255 | * @return the method hash for the specified method |
| 256 | */ |
| 257 | private static long getMethodHash(Method method) { |
| 258 | return methodToHash_Maps.get(method.getDeclaringClass()).get(method); |
| 259 | } |
| 260 | |
| 261 | /** |
| 262 | * A weak hash map, mapping classes to weak hash maps that map |
| 263 | * method objects to method hashes. |
| 264 | **/ |
| 265 | private static class MethodToHash_Maps |
| 266 | extends WeakClassHashMap<Map<Method,Long>> |
| 267 | { |
| 268 | MethodToHash_Maps() {} |
| 269 | |
| 270 | protected Map<Method,Long> computeValue(Class<?> remoteClass) { |
| 271 | return new WeakHashMap<Method,Long>() { |
| 272 | public synchronized Long get(Object key) { |
| 273 | Long hash = super.get(key); |
| 274 | if (hash == null) { |
| 275 | Method method = (Method) key; |
| 276 | hash = Util.computeMethodHash(method); |
| 277 | put(method, hash); |
| 278 | } |
| 279 | return hash; |
| 280 | } |
| 281 | }; |
| 282 | } |
| 283 | } |
| 284 | } |