ObjectStreamConstants


1   /*
2    * @(#)ObjectStreamConstants.java   1.34 04/01/12
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.io;
9   
10  /**
11   * Constants written into the Object Serialization Stream. 
12   *
13   * @author  unascribed
14   * @version 1.34, 01/12/04
15   * @since JDK 1.1
16   */
17  public interface ObjectStreamConstants {
18  
19      /**
20       * Magic number that is written to the stream header.
21       */
22      final static short STREAM_MAGIC = (short)0xaced;
23  
24      /**
25       * Version number that is written to the stream header.
26       */
27      final static short STREAM_VERSION = 5;
28  
29      /* Each item in the stream is preceded by a tag
30       */
31  
32      /** 
33       * First tag value.
34       */
35      final static byte TC_BASE = 0x70;
36  
37      /**
38       * Null object reference.
39       */
40      final static byte TC_NULL =     (byte)0x70;
41  
42      /**
43       * Reference to an object already written into the stream.
44       */
45      final static byte TC_REFERENCE =    (byte)0x71;
46  
47      /**
48       * new Class Descriptor.
49       */
50      final static byte TC_CLASSDESC =    (byte)0x72;
51  
52      /**
53       * new Object.
54       */
55      final static byte TC_OBJECT =   (byte)0x73;
56  
57      /** 
58       * new String.
59       */
60      final static byte TC_STRING =   (byte)0x74;
61  
62      /**
63       * new Array.
64       */
65      final static byte TC_ARRAY =    (byte)0x75;
66  
67      /**
68       * Reference to Class.
69       */
70      final static byte TC_CLASS =    (byte)0x76;
71  
72      /**
73       * Block of optional data. Byte following tag indicates number
74       * of bytes in this block data.
75       */
76      final static byte TC_BLOCKDATA =    (byte)0x77;
77  
78      /** 
79       * End of optional block data blocks for an object.
80       */
81      final static byte TC_ENDBLOCKDATA = (byte)0x78;
82  
83      /**
84       * Reset stream context. All handles written into stream are reset.
85       */
86      final static byte TC_RESET =    (byte)0x79;
87      
88      /**
89       * long Block data. The long following the tag indicates the
90       * number of bytes in this block data.
91       */
92      final static byte TC_BLOCKDATALONG= (byte)0x7A;
93      
94      /**
95       * Exception during write. 
96       */
97      final static byte TC_EXCEPTION =    (byte)0x7B;
98  
99      /**
100      * Long string.
101      */
102     final static byte TC_LONGSTRING =   (byte)0x7C;
103 
104     /**
105      * new Proxy Class Descriptor.
106      */
107     final static byte TC_PROXYCLASSDESC =   (byte)0x7D;
108 
109     /**
110      * new Enum constant.
111      */
112     final static byte TC_ENUM =     (byte)0x7E;
113 
114     /** 
115      * Last tag value.
116      */
117     final static byte TC_MAX =      (byte)0x7E;
118 
119     /**
120      * First wire handle to be assigned. 
121      */
122     final static int baseWireHandle = 0x7e0000;
123 
124 
125     /******************************************************/
126     /* Bit masks for ObjectStreamClass flag.*/
127 
128     /** 
129      * Bit mask for ObjectStreamClass flag. Indicates a Serializable class 
130      * defines its own writeObject method.
131      */
132     final static byte SC_WRITE_METHOD = 0x01;
133 
134     /**
135      * Bit mask for ObjectStreamClass flag. Indicates Externalizable data 
136      * written in Block Data mode.
137      * Added for PROTOCOL_VERSION_2.
138      *
139      * @see #PROTOCOL_VERSION_2
140      * @since 1.2
141      */
142     final static byte SC_BLOCK_DATA = 0x08;  
143 
144     /**
145      * Bit mask for ObjectStreamClass flag. Indicates class is Serializable.
146      */
147     final static byte SC_SERIALIZABLE = 0x02;
148 
149     /**
150      * Bit mask for ObjectStreamClass flag. Indicates class is Externalizable.
151      */
152     final static byte SC_EXTERNALIZABLE = 0x04;
153 
154     /**
155      * Bit mask for ObjectStreamClass flag. Indicates class is an enum type.
156      */
157     final static byte SC_ENUM = 0x10;
158 
159     
160     /* *******************************************************************/
161     /* Security permissions */
162 
163     /**
164      * Enable substitution of one object for another during 
165      * serialization/deserialization.
166      *
167      * @see java.io.ObjectOutputStream#enableReplaceObject(boolean)
168      * @see java.io.ObjectInputStream#enableResolveObject(boolean)
169      * @since 1.2
170      */
171     final static SerializablePermission   SUBSTITUTION_PERMISSION =
172                            new SerializablePermission  ("enableSubstitution");
173 
174     /**
175      * Enable overriding of readObject and writeObject.
176      *
177      * @see java.io.ObjectOutputStream#writeObjectOverride(Object)
178      * @see java.io.ObjectInputStream#readObjectOverride()
179      * @since 1.2
180      */
181     final static SerializablePermission   SUBCLASS_IMPLEMENTATION_PERMISSION =
182                     new SerializablePermission  ("enableSubclassImplementation");
183    /**
184     * A Stream Protocol Version. <p>
185     * 
186     * All externalizable data is written in JDK 1.1 external data 
187     * format after calling this method. This version is needed to write 
188     * streams containing Externalizable data that can be read by 
189     * pre-JDK 1.1.6 JVMs.
190     *
191     * @see java.io.ObjectOutputStream#useProtocolVersion(int)
192     * @since 1.2
193     */
194     public final static int PROTOCOL_VERSION_1 = 1;
195 
196     
197    /**
198     * A Stream Protocol Version. <p>
199     * 
200     * This protocol is written by JVM 1.2.
201     *
202     * Externalizable data is written in block data mode and is 
203     * terminated with TC_ENDBLOCKDATA. Externalizable classdescriptor
204     * flags has SC_BLOCK_DATA enabled. JVM 1.1.6 and greater can 
205     * read this format change.
206     *
207     * Enables writing a nonSerializable class descriptor into the
208     * stream. The serialVersionUID of a nonSerializable class is 
209     * set to 0L. 
210     *
211     * @see java.io.ObjectOutputStream#useProtocolVersion(int)
212     * @see #SC_BLOCK_DATA
213     * @since 1.2
214     */
215     public final static int PROTOCOL_VERSION_2 = 2;
216 }
217
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