Java example source code file (ObjectStreamConstants.java)

This example Java source code file (ObjectStreamConstants.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

protocol_version_1, sc_block_data, sc_externalizable, serializablepermission, stream_magic, stream_version, tc_array, tc_endblockdata, tc_exception, tc_longstring, tc_max, tc_null, tc_object, tc_reference

The ObjectStreamConstants.java Java example source code

/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.io;

/**
 * Constants written into the Object Serialization Stream.
 *
 * @author  unascribed
 * @since JDK 1.1
 */
public interface ObjectStreamConstants {

    /**
     * Magic number that is written to the stream header.
     */
    final static short STREAM_MAGIC = (short)0xaced;

    /**
     * Version number that is written to the stream header.
     */
    final static short STREAM_VERSION = 5;

    /* Each item in the stream is preceded by a tag
     */

    /**
     * First tag value.
     */
    final static byte TC_BASE = 0x70;

    /**
     * Null object reference.
     */
    final static byte TC_NULL =         (byte)0x70;

    /**
     * Reference to an object already written into the stream.
     */
    final static byte TC_REFERENCE =    (byte)0x71;

    /**
     * new Class Descriptor.
     */
    final static byte TC_CLASSDESC =    (byte)0x72;

    /**
     * new Object.
     */
    final static byte TC_OBJECT =       (byte)0x73;

    /**
     * new String.
     */
    final static byte TC_STRING =       (byte)0x74;

    /**
     * new Array.
     */
    final static byte TC_ARRAY =        (byte)0x75;

    /**
     * Reference to Class.
     */
    final static byte TC_CLASS =        (byte)0x76;

    /**
     * Block of optional data. Byte following tag indicates number
     * of bytes in this block data.
     */
    final static byte TC_BLOCKDATA =    (byte)0x77;

    /**
     * End of optional block data blocks for an object.
     */
    final static byte TC_ENDBLOCKDATA = (byte)0x78;

    /**
     * Reset stream context. All handles written into stream are reset.
     */
    final static byte TC_RESET =        (byte)0x79;

    /**
     * long Block data. The long following the tag indicates the
     * number of bytes in this block data.
     */
    final static byte TC_BLOCKDATALONG= (byte)0x7A;

    /**
     * Exception during write.
     */
    final static byte TC_EXCEPTION =    (byte)0x7B;

    /**
     * Long string.
     */
    final static byte TC_LONGSTRING =   (byte)0x7C;

    /**
     * new Proxy Class Descriptor.
     */
    final static byte TC_PROXYCLASSDESC =       (byte)0x7D;

    /**
     * new Enum constant.
     * @since 1.5
     */
    final static byte TC_ENUM =         (byte)0x7E;

    /**
     * Last tag value.
     */
    final static byte TC_MAX =          (byte)0x7E;

    /**
     * First wire handle to be assigned.
     */
    final static int baseWireHandle = 0x7e0000;


    /******************************************************/
    /* Bit masks for ObjectStreamClass flag.*/

    /**
     * Bit mask for ObjectStreamClass flag. Indicates a Serializable class
     * defines its own writeObject method.
     */
    final static byte SC_WRITE_METHOD = 0x01;

    /**
     * Bit mask for ObjectStreamClass flag. Indicates Externalizable data
     * written in Block Data mode.
     * Added for PROTOCOL_VERSION_2.
     *
     * @see #PROTOCOL_VERSION_2
     * @since 1.2
     */
    final static byte SC_BLOCK_DATA = 0x08;

    /**
     * Bit mask for ObjectStreamClass flag. Indicates class is Serializable.
     */
    final static byte SC_SERIALIZABLE = 0x02;

    /**
     * Bit mask for ObjectStreamClass flag. Indicates class is Externalizable.
     */
    final static byte SC_EXTERNALIZABLE = 0x04;

    /**
     * Bit mask for ObjectStreamClass flag. Indicates class is an enum type.
     * @since 1.5
     */
    final static byte SC_ENUM = 0x10;


    /* *******************************************************************/
    /* Security permissions */

    /**
     * Enable substitution of one object for another during
     * serialization/deserialization.
     *
     * @see java.io.ObjectOutputStream#enableReplaceObject(boolean)
     * @see java.io.ObjectInputStream#enableResolveObject(boolean)
     * @since 1.2
     */
    final static SerializablePermission SUBSTITUTION_PERMISSION =
                           new SerializablePermission("enableSubstitution");

    /**
     * Enable overriding of readObject and writeObject.
     *
     * @see java.io.ObjectOutputStream#writeObjectOverride(Object)
     * @see java.io.ObjectInputStream#readObjectOverride()
     * @since 1.2
     */
    final static SerializablePermission SUBCLASS_IMPLEMENTATION_PERMISSION =
                    new SerializablePermission("enableSubclassImplementation");
   /**
    * A Stream Protocol Version. <p>
    *
    * All externalizable data is written in JDK 1.1 external data
    * format after calling this method. This version is needed to write
    * streams containing Externalizable data that can be read by
    * pre-JDK 1.1.6 JVMs.
    *
    * @see java.io.ObjectOutputStream#useProtocolVersion(int)
    * @since 1.2
    */
    public final static int PROTOCOL_VERSION_1 = 1;


   /**
    * A Stream Protocol Version. <p>
    *
    * This protocol is written by JVM 1.2.
    *
    * Externalizable data is written in block data mode and is
    * terminated with TC_ENDBLOCKDATA. Externalizable class descriptor
    * flags has SC_BLOCK_DATA enabled. JVM 1.1.6 and greater can
    * read this format change.
    *
    * Enables writing a nonSerializable class descriptor into the
    * stream. The serialVersionUID of a nonSerializable class is
    * set to 0L.
    *
    * @see java.io.ObjectOutputStream#useProtocolVersion(int)
    * @see #SC_BLOCK_DATA
    * @since 1.2
    */
    public final static int PROTOCOL_VERSION_2 = 2;
}