- /*
- * @(#)RemoteObject.java 1.33 03/12/19
- *
- * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
-
- package java.rmi.server;
-
- import java.rmi.Remote;
- import java.rmi.NoSuchObjectException;
- import java.lang.reflect.Proxy;
- import sun.rmi.server.Util;
-
- /**
- * The <code>RemoteObject</code> class implements the
- * <code>java.lang.Object</code> behavior for remote objects.
- * <code>RemoteObject</code> provides the remote semantics of Object by
- * implementing methods for hashCode, equals, and toString.
- *
- * @author Ann Wollrath
- * @author Laird Dornin
- * @author Peter Jones
- * @version 1.33, 03/12/19
- * @since JDK1.1
- */
- public abstract class RemoteObject implements Remote, java.io.Serializable {
-
- /** The object's remote reference. */
- transient protected RemoteRef ref;
-
- /** indicate compatibility with JDK 1.1.x version of class */
- private static final long serialVersionUID = -3215090123894869218L;
-
- /**
- * Creates a remote object.
- */
- protected RemoteObject() {
- ref = null;
- }
-
- /**
- * Creates a remote object, initialized with the specified remote
- * reference.
- * @param newref remote reference
- */
- protected RemoteObject(RemoteRef newref) {
- ref = newref;
- }
-
- /**
- * Returns the remote reference for the remote object.
- *
- * <p>Note: The object returned from this method may be an instance of
- * an implementation-specific class. The <code>RemoteObject</code>
- * class ensures serialization portability of its instances' remote
- * references through the behavior of its custom
- * <code>writeObject</code> and <code>readObject</code> methods. An
- * instance of <code>RemoteRef</code> should not be serialized outside
- * of its <code>RemoteObject</code> wrapper instance or the result may
- * be unportable.
- *
- * @return remote reference for the remote object
- * @since 1.2
- */
- public RemoteRef getRef() {
- return ref;
- }
-
- /**
- * Returns the stub for the remote object <code>obj</code> passed
- * as a parameter. This operation is only valid <i>after</i>
- * the object has been exported.
- * @param obj the remote object whose stub is needed
- * @return the stub for the remote object, <code>obj</code>.
- * @exception NoSuchObjectException if the stub for the
- * remote object could not be found.
- * @since 1.2
- */
- public static Remote toStub(Remote obj) throws NoSuchObjectException {
- if (obj instanceof RemoteStub ||
- (obj != null &&
- Proxy.isProxyClass(obj.getClass()) &&
- Proxy.getInvocationHandler(obj) instanceof
- RemoteObjectInvocationHandler))
- {
- return obj;
- } else {
- return sun.rmi.transport.ObjectTable.getStub(obj);
- }
- }
-
- /**
- * Returns a hashcode for a remote object. Two remote object stubs
- * that refer to the same remote object will have the same hash code
- * (in order to support remote objects as keys in hash tables).
- *
- * @see java.util.Hashtable
- */
- public int hashCode() {
- return (ref == null) ? super.hashCode() : ref.remoteHashCode();
- }
-
- /**
- * Compares two remote objects for equality.
- * Returns a boolean that indicates whether this remote object is
- * equivalent to the specified Object. This method is used when a
- * remote object is stored in a hashtable.
- * If the specified Object is not itself an instance of RemoteObject,
- * then this method delegates by returning the result of invoking the
- * <code>equals</code> method of its parameter with this remote object
- * as the argument.
- * @param obj the Object to compare with
- * @return true if these Objects are equal; false otherwise.
- * @see java.util.Hashtable
- */
- public boolean equals(Object obj) {
- if (obj instanceof RemoteObject) {
- if (ref == null) {
- return obj == this;
- } else {
- return ref.remoteEquals(((RemoteObject)obj).ref);
- }
- } else if (obj != null) {
- /*
- * Fix for 4099660: if object is not an instance of RemoteObject,
- * use the result of its equals method, to support symmetry is a
- * remote object implementation class that does not extend
- * RemoteObject wishes to support equality with its stub objects.
- */
- return obj.equals(this);
- } else {
- return false;
- }
- }
-
- /**
- * Returns a String that represents the value of this remote object.
- */
- public String toString() {
- String classname = Util.getUnqualifiedName(getClass());
- return (ref == null) ? classname :
- classname + "[" + ref.remoteToString() + "]";
- }
-
- /**
- * <code>writeObject</code> for custom serialization.
- *
- * <p>This method writes this object's serialized form for this class
- * as follows:
- *
- * <p>The {@link RemoteRef#getRefClass(java.io.ObjectOutput) getRefClass}
- * method is invoked on this object's <code>ref</code> field
- * to obtain its external ref type name.
- * If the value returned by <code>getRefClass</code> was
- * a non-<code>null</code> string of length greater than zero,
- * the <code>writeUTF</code> method is invoked on <code>out</code>
- * with the value returned by <code>getRefClass</code>, and then
- * the <code>writeExternal</code> method is invoked on
- * this object's <code>ref</code> field passing <code>out</code>
- * as the argument; otherwise,
- * the <code>writeUTF</code> method is invoked on <code>out</code>
- * with a zero-length string (<code>""</code>), and then
- * the <code>writeObject</code> method is invoked on <code>out</code>
- * passing this object's <code>ref</code> field as the argument.
- *
- * @serialData
- *
- * The serialized data for this class comprises a string (written with
- * <code>ObjectOutput.writeUTF</code>) that is either the external
- * ref type name of the contained <code>RemoteRef</code> instance
- * (the <code>ref</code> field) or a zero-length string, followed by
- * either the external form of the <code>ref</code> field as written by
- * its <code>writeExternal</code> method if the string was of non-zero
- * length, or the serialized form of the <code>ref</code> field as
- * written by passing it to the serialization stream's
- * <code>writeObject</code> if the string was of zero length.
- *
- * <p>If this object is an instance of
- * {@link RemoteStub} or {@link RemoteObjectInvocationHandler}
- * that was returned from any of
- * the <code>UnicastRemoteObject.exportObject</code> methods
- * and custom socket factories are not used,
- * the external ref type name is <code>"UnicastRef"</code>.
- *
- * If this object is an instance of
- * <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
- * that was returned from any of
- * the <code>UnicastRemoteObject.exportObject</code> methods
- * and custom socket factories are used,
- * the external ref type name is <code>"UnicastRef2"</code>.
- *
- * If this object is an instance of
- * <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
- * that was returned from any of
- * the <code>java.rmi.activation.Activatable.exportObject</code> methods,
- * the external ref type name is <code>"ActivatableRef"</code>.
- *
- * If this object is an instance of
- * <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
- * that was returned from
- * the <code>RemoteObject.toStub</code> method (and the argument passed
- * to <code>toStub</code> was not itself a <code>RemoteStub</code>),
- * the external ref type name is a function of how the remote object
- * passed to <code>toStub</code> was exported, as described above.
- *
- * If this object is an instance of
- * <code>RemoteStub</code> or <code>RemoteObjectInvocationHandler</code>
- * that was originally created via deserialization,
- * the external ref type name is the same as that which was read
- * when this object was deserialized.
- *
- * <p>If this object is an instance of
- * <code>java.rmi.server.UnicastRemoteObject</code> that does not
- * use custom socket factories,
- * the external ref type name is <code>"UnicastServerRef"</code>.
- *
- * If this object is an instance of
- * <code>UnicastRemoteObject</code> that does
- * use custom socket factories,
- * the external ref type name is <code>"UnicastServerRef2"</code>.
- *
- * <p>Following is the data that must be written by the
- * <code>writeExternal</code> method and read by the
- * <code>readExternal</code> method of <code>RemoteRef</code>
- * implementation classes that correspond to the each of the
- * defined external ref type names:
- *
- * <p>For <code>"UnicastRef"</code>:
- *
- * <ul>
- *
- * <li>the hostname of the referenced remote object,
- * written by {@link java.io.ObjectOutput#writeUTF(String)}
- *
- * <li>the port of the referenced remote object,
- * written by {@link java.io.ObjectOutput#writeInt(int)}
- *
- * <li>the data written as a result of calling
- * {link java.rmi.server.ObjID#write(java.io.ObjectOutput)}
- * on the <code>ObjID</code> instance contained in the reference
- *
- * <li>the boolean value <code>false</code>,
- * written by {@link java.io.ObjectOutput#writeBoolean(boolean)}
- *
- * </ul>
- *
- * <p>For <code>"UnicastRef2"</code> with a
- * <code>null</code> client socket factory:
- *
- * <ul>
- *
- * <li>the byte value <code>0x00</code>
- * (indicating <code>null</code> client socket factory),
- * written by {@link java.io.ObjectOutput#writeByte(int)}
- *
- * <li>the hostname of the referenced remote object,
- * written by {@link java.io.ObjectOutput#writeUTF(String)}
- *
- * <li>the port of the referenced remote object,
- * written by {@link java.io.ObjectOutput#writeInt(int)}
- *
- * <li>the data written as a result of calling
- * {link java.rmi.server.ObjID#write(java.io.ObjectOutput)}
- * on the <code>ObjID</code> instance contained in the reference
- *
- * <li>the boolean value <code>false</code>,
- * written by {@link java.io.ObjectOutput#writeBoolean(boolean)}
- *
- * </ul>
- *
- * <p>For <code>"UnicastRef2"</code> with a
- * non-<code>null</code> client socket factory:
- *
- * <ul>
- *
- * <li>the byte value <code>0x01</code>
- * (indicating non-<code>null</code> client socket factory),
- * written by {@link java.io.ObjectOutput#writeByte(int)}
- *
- * <li>the hostname of the referenced remote object,
- * written by {@link java.io.ObjectOutput#writeUTF(String)}
- *
- * <li>the port of the referenced remote object,
- * written by {@link java.io.ObjectOutput#writeInt(int)}
- *
- * <li>a client socket factory (object of type
- * <code>java.rmi.server.RMIClientSocketFactory</code>),
- * written by passing it to an invocation of
- * <code>writeObject</code> on the stream instance
- *
- * <li>the data written as a result of calling
- * {link java.rmi.server.ObjID#write(java.io.ObjectOutput)}
- * on the <code>ObjID</code> instance contained in the reference
- *
- * <li>the boolean value <code>false</code>,
- * written by {@link java.io.ObjectOutput#writeBoolean(boolean)}
- *
- * </ul>
- *
- * <p>For <code>"ActivatableRef"</code> with a
- * <code>null</code> nested remote reference:
- *
- * <ul>
- *
- * <li>an instance of
- * <code>java.rmi.activation.ActivationID</code>,
- * written by passing it to an invocation of
- * <code>writeObject</code> on the stream instance
- *
- * <li>a zero-length string (<code>""</code>),
- * written by {@link java.io.ObjectOutput#writeUTF(String)}
- *
- * </ul>
- *
- * <p>For <code>"ActivatableRef"</code> with a
- * non-<code>null</code> nested remote reference:
- *
- * <ul>
- *
- * <li>an instance of
- * <code>java.rmi.activation.ActivationID</code>,
- * written by passing it to an invocation of
- * <code>writeObject</code> on the stream instance
- *
- * <li>the external ref type name of the nested remote reference,
- * which must be <code>"UnicastRef2"</code>,
- * written by {@link java.io.ObjectOutput#writeUTF(String)}
- *
- * <li>the external form of the nested remote reference,
- * written by invoking its <code>writeExternal</code> method
- * with the stream instance
- * (see the description of the external form for
- * <code>"UnicastRef2"</code> above)
- *
- * </ul>
- *
- * <p>For <code>"UnicastServerRef"</code> and
- * <code>"UnicastServerRef2"</code>, no data is written by the
- * <code>writeExternal</code> method or read by the
- * <code>readExternal</code> method.
- */
- private void writeObject(java.io.ObjectOutputStream out)
- throws java.io.IOException, java.lang.ClassNotFoundException
- {
- if (ref == null) {
- throw new java.rmi.MarshalException("Invalid remote object");
- } else {
- String refClassName = ref.getRefClass(out);
- if (refClassName == null || refClassName.length() == 0) {
- /*
- * No reference class name specified, so serialize
- * remote reference.
- */
- out.writeUTF("");
- out.writeObject(ref);
- } else {
- /*
- * Built-in reference class specified, so delegate
- * to reference to write out its external form.
- */
- out.writeUTF(refClassName);
- ref.writeExternal(out);
- }
- }
- }
-
- /**
- * <code>readObject</code> for custom serialization.
- *
- * <p>This method reads this object's serialized form for this class
- * as follows:
- *
- * <p>The <code>readUTF</code> method is invoked on <code>in</code>
- * to read the external ref type name for the <code>RemoteRef</code>
- * instance to be filled in to this object's <code>ref</code> field.
- * If the string returned by <code>readUTF</code> has length zero,
- * the <code>readObject</code> method is invoked on <code>in</code>,
- * and than the value returned by <code>readObject</code> is cast to
- * <code>RemoteRef</code> and this object's <code>ref</code> field is
- * set to that value.
- * Otherwise, this object's <code>ref</code> field is set to a
- * <code>RemoteRef</code> instance that is created of an
- * implementation-specific class corresponding to the external ref
- * type name returned by <code>readUTF</code>, and then
- * the <code>readExternal</code> method is invoked on
- * this object's <code>ref</code> field.
- *
- * <p>If the external ref type name is
- * <code>"UnicastRef"</code>, <code>"UnicastServerRef"</code>,
- * <code>"UnicastRef2"</code>, <code>"UnicastServerRef2"</code>,
- * or <code>"ActivatableRef"</code>, a corresponding
- * implementation-specific class must be found, and its
- * <code>readExternal</code> method must read the serial data
- * for that external ref type name as specified to be written
- * in the <b>serialData</b> documentation for this class.
- * If the external ref type name is any other string (of non-zero
- * length), a <code>ClassNotFoundException</code> will be thrown,
- * unless the implementation provides an implementation-specific
- * class corresponding to that external ref type name, in which
- * case this object's <code>ref</code> field will be set to an
- * instance of that implementation-specific class.
- */
- private void readObject(java.io.ObjectInputStream in)
- throws java.io.IOException, java.lang.ClassNotFoundException
- {
- String refClassName = in.readUTF();
- if (refClassName == null || refClassName.length() == 0) {
- /*
- * No reference class name specified, so construct
- * remote reference from its serialized form.
- */
- ref = (RemoteRef) in.readObject();
- } else {
- /*
- * Built-in reference class specified, so delegate to
- * internal reference class to initialize its fields from
- * its external form.
- */
- String internalRefClassName =
- RemoteRef.packagePrefix + "." + refClassName;
- Class refClass = Class.forName(internalRefClassName);
- try {
- ref = (RemoteRef) refClass.newInstance();
-
- /*
- * If this step fails, assume we found an internal
- * class that is not meant to be a serializable ref
- * type.
- */
- } catch (InstantiationException e) {
- throw new ClassNotFoundException(internalRefClassName, e);
- } catch (IllegalAccessException e) {
- throw new ClassNotFoundException(internalRefClassName, e);
- } catch (ClassCastException e) {
- throw new ClassNotFoundException(internalRefClassName, e);
- }
- ref.readExternal(in);
- }
- }
- }