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/*
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* Copyright 1996-2003 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package java.rmi.server;
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import java.rmi.Remote;
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import java.rmi.NoSuchObjectException;
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import java.lang.reflect.Proxy;
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import sun.rmi.server.Util;
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/**
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* The <code>RemoteObject</code> class implements the
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* <code>java.lang.Object</code> behavior for remote objects.
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* <code>RemoteObject</code> provides the remote semantics of Object by
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* implementing methods for hashCode, equals, and toString.
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*
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* @author Ann Wollrath
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* @author Laird Dornin
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* @author Peter Jones
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* @since JDK1.1
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*/
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public abstract class RemoteObject implements Remote, java.io.Serializable {
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/** The object's remote reference. */
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transient protected RemoteRef ref;
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/** indicate compatibility with JDK 1.1.x version of class */
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private static final long serialVersionUID = -3215090123894869218L;
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/**
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* Creates a remote object.
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*/
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protected RemoteObject() {
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ref = null;
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}
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/**
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* Creates a remote object, initialized with the specified remote
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* reference.
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* @param newref remote reference
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*/
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protected RemoteObject(RemoteRef newref) {
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ref = newref;
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}
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/**
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* Returns the remote reference for the remote object.
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*
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* <p>Note: The object returned from this method may be an instance of
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* an implementation-specific class. The <code>RemoteObject</code>
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* class ensures serialization portability of its instances' remote
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* references through the behavior of its custom
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* <code>writeObject</code> and <code>readObject</code> methods. An
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* instance of <code>RemoteRef</code> should not be serialized outside
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* of its <code>RemoteObject</code> wrapper instance or the result may
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* be unportable.
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*
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* @return remote reference for the remote object
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* @since 1.2
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*/
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public RemoteRef getRef() {
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return ref;
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}
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/**
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* Returns the stub for the remote object <code>obj</code> passed
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* as a parameter. This operation is only valid <i>after</i>
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* the object has been exported.
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* @param obj the remote object whose stub is needed
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* @return the stub for the remote object, <code>obj</code>.
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* @exception NoSuchObjectException if the stub for the
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* remote object could not be found.
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* @since 1.2
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*/
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public static Remote toStub(Remote obj) throws NoSuchObjectException {
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if (obj instanceof RemoteStub ||
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(obj != null &&
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Proxy.isProxyClass(obj.getClass()) &&
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Proxy.getInvocationHandler(obj) instanceof
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RemoteObjectInvocationHandler))
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{
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return obj;
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} else {
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return sun.rmi.transport.ObjectTable.getStub(obj);
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}
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}
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/**
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* Returns a hashcode for a remote object. Two remote object stubs
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* that refer to the same remote object will have the same hash code
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* (in order to support remote objects as keys in hash tables).
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*
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* @see java.util.Hashtable
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*/
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public int hashCode() {
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return (ref == null) ? super.hashCode() : ref.remoteHashCode();
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}
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/**
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* Compares two remote objects for equality.
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* Returns a boolean that indicates whether this remote object is
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* equivalent to the specified Object. This method is used when a
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* remote object is stored in a hashtable.
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* If the specified Object is not itself an instance of RemoteObject,
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* then this method delegates by returning the result of invoking the
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* <code>equals</code> method of its parameter with this remote object
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* as the argument.
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* @param obj the Object to compare with
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* @return true if these Objects are equal; false otherwise.
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* @see java.util.Hashtable
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*/
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public boolean equals(Object obj) {
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if (obj instanceof RemoteObject) {
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if (ref == null) {
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return obj == this;
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} else {
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return ref.remoteEquals(((RemoteObject)obj).ref);
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}
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} else if (obj != null) {
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/*
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* Fix for 4099660: if object is not an instance of RemoteObject,
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* use the result of its equals method, to support symmetry is a
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* remote object implementation class that does not extend
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* RemoteObject wishes to support equality with its stub objects.
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*/
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return obj.equals(this);
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} else {
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return false;
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}
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}
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/**
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* Returns a String that represents the value of this remote object.
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*/
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public String toString() {
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String classname = Util.getUnqualifiedName(getClass());
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return (ref == null) ? classname :
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classname + "[" + ref.remoteToString() + "]";
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}
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/**
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* <code>writeObject</code> for custom serialization.
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*
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* <p>This method writes this object's serialized form for this class
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* as follows:
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*
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* <p>The {@link RemoteRef#getRefClass(java.io.ObjectOutput) getRefClass}
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* method is invoked on this object's <code>ref</code> field
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* to obtain its external ref type name.
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* If the value returned by <code>getRefClass</code> was
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* a non-<code>null</code> string of length greater than zero,
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* the <code>writeUTF</code> method is invoked on <code>out</code>
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* with the value returned by <code>getRefClass</code>, and then
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* the <code>writeExternal</code> method is invoked on
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* this object's <code>ref</code> field passing <code>out</code>
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* as the argument; otherwise,
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* the <code>writeUTF</code> method is invoked on <code>out</code>
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* with a zero-length string (<code>""</code>), and then
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* the <code>writeObject</code> method is invoked on <code>out</code>
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* passing this object's <code>ref</code> field as the argument.
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*
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* @serialData
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*
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* The serialized data for this class comprises a string (written with
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* <code>ObjectOutput.writeUTF</code>) that is either the external
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* ref type name of the contained <code>RemoteRef</code> instance
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* (the <code>ref</code> field) or a zero-length string, followed by
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* either the external form of the <code>ref</code> field as written by
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* its <code>writeExternal</code> method if the string was of non-zero
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* length, or the serialized form of the <code>ref</code> field as
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* written by passing it to the serialization stream's
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* <code>writeObject</code> if the string was of zero length.
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*
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* <p>If this object is an instance of
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* {@link RemoteStub} or {@link RemoteObjectInvocationHandler}
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* that was returned from any of
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* the <code>UnicastRemoteObject.exportObject</code> methods
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* and custom socket factories are not used,
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* the external ref type name is <code>"UnicastRef"</code>.
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*
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* If this object is an instance of
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* <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
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* that was returned from any of
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* the <code>UnicastRemoteObject.exportObject</code> methods
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* and custom socket factories are used,
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* the external ref type name is <code>"UnicastRef2"</code>.
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*
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* If this object is an instance of
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* <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
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* that was returned from any of
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* the <code>java.rmi.activation.Activatable.exportObject</code> methods,
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* the external ref type name is <code>"ActivatableRef"</code>.
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*
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* If this object is an instance of
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* <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
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* that was returned from
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* the <code>RemoteObject.toStub</code> method (and the argument passed
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* to <code>toStub</code> was not itself a <code>RemoteStub</code>),
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* the external ref type name is a function of how the remote object
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* passed to <code>toStub</code> was exported, as described above.
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*
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* If this object is an instance of
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* <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
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* that was originally created via deserialization,
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* the external ref type name is the same as that which was read
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* when this object was deserialized.
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*
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* <p>If this object is an instance of
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* <code>java.rmi.server.UnicastRemoteObject</code> that does not
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* use custom socket factories,
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* the external ref type name is <code>"UnicastServerRef"</code>.
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*
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* If this object is an instance of
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* <code>UnicastRemoteObject</code> that does
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* use custom socket factories,
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* the external ref type name is <code>"UnicastServerRef2"</code>.
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*
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* <p>Following is the data that must be written by the
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* <code>writeExternal</code> method and read by the
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* <code>readExternal</code> method of <code>RemoteRef</code>
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* implementation classes that correspond to the each of the
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* defined external ref type names:
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*
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* <p>For <code>"UnicastRef"</code>:
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*
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* <ul>
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*
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* <li>the hostname of the referenced remote object,
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* written by {@link java.io.ObjectOutput#writeUTF(String)}
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*
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* <li>the port of the referenced remote object,
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* written by {@link java.io.ObjectOutput#writeInt(int)}
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*
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* <li>the data written as a result of calling
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* {link java.rmi.server.ObjID#write(java.io.ObjectOutput)}
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* on the <code>ObjID</code> instance contained in the reference
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*
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* <li>the boolean value <code>false</code>,
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* written by {@link java.io.ObjectOutput#writeBoolean(boolean)}
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*
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* </ul>
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*
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* <p>For <code>"UnicastRef2"</code> with a
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* <code>null</code> client socket factory:
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*
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* <ul>
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*
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* <li>the byte value <code>0x00</code>
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* (indicating <code>null</code> client socket factory),
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* written by {@link java.io.ObjectOutput#writeByte(int)}
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*
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* <li>the hostname of the referenced remote object,
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* written by {@link java.io.ObjectOutput#writeUTF(String)}
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*
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* <li>the port of the referenced remote object,
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* written by {@link java.io.ObjectOutput#writeInt(int)}
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*
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* <li>the data written as a result of calling
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* {link java.rmi.server.ObjID#write(java.io.ObjectOutput)}
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* on the <code>ObjID</code> instance contained in the reference
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*
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* <li>the boolean value <code>false</code>,
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* written by {@link java.io.ObjectOutput#writeBoolean(boolean)}
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*
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* </ul>
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*
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* <p>For <code>"UnicastRef2"</code> with a
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* non-<code>null</code> client socket factory:
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*
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* <ul>
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*
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* <li>the byte value <code>0x01</code>
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* (indicating non-<code>null</code> client socket factory),
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* written by {@link java.io.ObjectOutput#writeByte(int)}
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*
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* <li>the hostname of the referenced remote object,
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* written by {@link java.io.ObjectOutput#writeUTF(String)}
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*
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* <li>the port of the referenced remote object,
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* written by {@link java.io.ObjectOutput#writeInt(int)}
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*
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* <li>a client socket factory (object of type
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* <code>java.rmi.server.RMIClientSocketFactory</code>),
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* written by passing it to an invocation of
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* <code>writeObject</code> on the stream instance
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*
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* <li>the data written as a result of calling
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* {link java.rmi.server.ObjID#write(java.io.ObjectOutput)}
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* on the <code>ObjID</code> instance contained in the reference
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*
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* <li>the boolean value <code>false</code>,
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* written by {@link java.io.ObjectOutput#writeBoolean(boolean)}
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*
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* </ul>
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*
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* <p>For <code>"ActivatableRef"</code> with a
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* <code>null</code> nested remote reference:
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*
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* <ul>
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*
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* <li>an instance of
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* <code>java.rmi.activation.ActivationID</code>,
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* written by passing it to an invocation of
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* <code>writeObject</code> on the stream instance
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*
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* <li>a zero-length string (<code>""</code>),
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* written by {@link java.io.ObjectOutput#writeUTF(String)}
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*
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* </ul>
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*
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* <p>For <code>"ActivatableRef"</code> with a
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* non-<code>null</code> nested remote reference:
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*
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* <ul>
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*
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* <li>an instance of
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* <code>java.rmi.activation.ActivationID</code>,
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* written by passing it to an invocation of
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* <code>writeObject</code> on the stream instance
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*
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* <li>the external ref type name of the nested remote reference,
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* which must be <code>"UnicastRef2"</code>,
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* written by {@link java.io.ObjectOutput#writeUTF(String)}
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*
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* <li>the external form of the nested remote reference,
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* written by invoking its <code>writeExternal</code> method
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* with the stream instance
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* (see the description of the external form for
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* <code>"UnicastRef2"</code> above)
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*
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* </ul>
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*
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* <p>For <code>"UnicastServerRef"</code> and
|
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* <code>"UnicastServerRef2"</code>, no data is written by the
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* <code>writeExternal</code> method or read by the
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* <code>readExternal</code> method.
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*/
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private void writeObject(java.io.ObjectOutputStream out)
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throws java.io.IOException, java.lang.ClassNotFoundException
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{
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if (ref == null) {
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throw new java.rmi.MarshalException("Invalid remote object");
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} else {
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String refClassName = ref.getRefClass(out);
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|
367 |
if (refClassName == null || refClassName.length() == 0) {
|
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/*
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369 |
* No reference class name specified, so serialize
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370 |
* remote reference.
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*/
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out.writeUTF("");
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out.writeObject(ref);
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} else {
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|
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/*
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* Built-in reference class specified, so delegate
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* to reference to write out its external form.
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*/
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out.writeUTF(refClassName);
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ref.writeExternal(out);
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}
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}
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383 |
}
|
|
384 |
|
|
385 |
/**
|
|
386 |
* <code>readObject</code> for custom serialization.
|
|
387 |
*
|
|
388 |
* <p>This method reads this object's serialized form for this class
|
|
389 |
* as follows:
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390 |
*
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|
391 |
* <p>The <code>readUTF</code> method is invoked on <code>in</code>
|
|
392 |
* to read the external ref type name for the <code>RemoteRef</code>
|
|
393 |
* instance to be filled in to this object's <code>ref</code> field.
|
|
394 |
* If the string returned by <code>readUTF</code> has length zero,
|
|
395 |
* the <code>readObject</code> method is invoked on <code>in</code>,
|
|
396 |
* and than the value returned by <code>readObject</code> is cast to
|
|
397 |
* <code>RemoteRef</code> and this object's <code>ref</code> field is
|
|
398 |
* set to that value.
|
|
399 |
* Otherwise, this object's <code>ref</code> field is set to a
|
|
400 |
* <code>RemoteRef</code> instance that is created of an
|
|
401 |
* implementation-specific class corresponding to the external ref
|
|
402 |
* type name returned by <code>readUTF</code>, and then
|
|
403 |
* the <code>readExternal</code> method is invoked on
|
|
404 |
* this object's <code>ref</code> field.
|
|
405 |
*
|
|
406 |
* <p>If the external ref type name is
|
|
407 |
* <code>"UnicastRef"</code>, <code>"UnicastServerRef"</code>,
|
|
408 |
* <code>"UnicastRef2"</code>, <code>"UnicastServerRef2"</code>,
|
|
409 |
* or <code>"ActivatableRef"</code>, a corresponding
|
|
410 |
* implementation-specific class must be found, and its
|
|
411 |
* <code>readExternal</code> method must read the serial data
|
|
412 |
* for that external ref type name as specified to be written
|
|
413 |
* in the <b>serialData</b> documentation for this class.
|
|
414 |
* If the external ref type name is any other string (of non-zero
|
|
415 |
* length), a <code>ClassNotFoundException</code> will be thrown,
|
|
416 |
* unless the implementation provides an implementation-specific
|
|
417 |
* class corresponding to that external ref type name, in which
|
|
418 |
* case this object's <code>ref</code> field will be set to an
|
|
419 |
* instance of that implementation-specific class.
|
|
420 |
*/
|
|
421 |
private void readObject(java.io.ObjectInputStream in)
|
|
422 |
throws java.io.IOException, java.lang.ClassNotFoundException
|
|
423 |
{
|
|
424 |
String refClassName = in.readUTF();
|
|
425 |
if (refClassName == null || refClassName.length() == 0) {
|
|
426 |
/*
|
|
427 |
* No reference class name specified, so construct
|
|
428 |
* remote reference from its serialized form.
|
|
429 |
*/
|
|
430 |
ref = (RemoteRef) in.readObject();
|
|
431 |
} else {
|
|
432 |
/*
|
|
433 |
* Built-in reference class specified, so delegate to
|
|
434 |
* internal reference class to initialize its fields from
|
|
435 |
* its external form.
|
|
436 |
*/
|
|
437 |
String internalRefClassName =
|
|
438 |
RemoteRef.packagePrefix + "." + refClassName;
|
|
439 |
Class refClass = Class.forName(internalRefClassName);
|
|
440 |
try {
|
|
441 |
ref = (RemoteRef) refClass.newInstance();
|
|
442 |
|
|
443 |
/*
|
|
444 |
* If this step fails, assume we found an internal
|
|
445 |
* class that is not meant to be a serializable ref
|
|
446 |
* type.
|
|
447 |
*/
|
|
448 |
} catch (InstantiationException e) {
|
|
449 |
throw new ClassNotFoundException(internalRefClassName, e);
|
|
450 |
} catch (IllegalAccessException e) {
|
|
451 |
throw new ClassNotFoundException(internalRefClassName, e);
|
|
452 |
} catch (ClassCastException e) {
|
|
453 |
throw new ClassNotFoundException(internalRefClassName, e);
|
|
454 |
}
|
|
455 |
ref.readExternal(in);
|
|
456 |
}
|
|
457 |
}
|
|
458 |
}
|