1 /*
2 * Copyright (c) 1996, 2015, Oracle and/or its affiliates. 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.io;
27
28 import java.lang.reflect.Field;
29 import jdk.internal.reflect.CallerSensitive;
30 import jdk.internal.reflect.Reflection;
31 import sun.reflect.misc.ReflectUtil;
32
33 /**
34 * A description of a Serializable field from a Serializable class. An array
35 * of ObjectStreamFields is used to declare the Serializable fields of a class.
36 *
37 * @author Mike Warres
38 * @author Roger Riggs
39 * @see ObjectStreamClass
40 * @since 1.2
41 */
42 public class ObjectStreamField
43 implements Comparable<Object>
44 {
45
46 /** field name */
47 private final String name;
48 /** canonical JVM signature of field type */
49 private final String signature;
50 /** field type (Object.class if unknown non-primitive type) */
51 private final Class<?> type;
52 /** whether or not to (de)serialize field values as unshared */
53 private final boolean unshared;
54 /** corresponding reflective field object, if any */
55 private final Field field;
56 /** offset of field value in enclosing field group */
57 private int offset = 0;
58
59 /**
60 * Create a Serializable field with the specified type. This field should
61 * be documented with a <code>serialField</code> tag.
62 *
63 * @param name the name of the serializable field
64 * @param type the <code>Class</code> object of the serializable field
65 */
66 public ObjectStreamField(String name, Class<?> type) {
67 this(name, type, false);
68 }
69
70 /**
71 * Creates an ObjectStreamField representing a serializable field with the
72 * given name and type. If unshared is false, values of the represented
73 * field are serialized and deserialized in the default manner--if the
74 * field is non-primitive, object values are serialized and deserialized as
75 * if they had been written and read by calls to writeObject and
76 * readObject. If unshared is true, values of the represented field are
77 * serialized and deserialized as if they had been written and read by
78 * calls to writeUnshared and readUnshared.
79 *
80 * @param name field name
81 * @param type field type
82 * @param unshared if false, write/read field values in the same manner
83 * as writeObject/readObject; if true, write/read in the same
84 * manner as writeUnshared/readUnshared
85 * @since 1.4
86 */
87 public ObjectStreamField(String name, Class<?> type, boolean unshared) {
88 if (name == null) {
89 throw new NullPointerException();
90 }
91 this.name = name;
92 this.type = type;
93 this.unshared = unshared;
94 signature = null; // will be lazily obtained from type
95 field = null;
96 }
97
98 /**
99 * Creates an ObjectStreamField representing a field with the given name,
100 * signature and unshared setting.
101 */
102 ObjectStreamField(String name, String signature, boolean unshared) {
103 if (name == null) {
104 throw new NullPointerException();
105 }
106 this.name = name;
107 this.signature = signature.intern();
108 this.unshared = unshared;
109 field = null;
110
111 switch (signature.charAt(0)) {
112 case 'Z': type = Boolean.TYPE; break;
113 case 'B': type = Byte.TYPE; break;
114 case 'C': type = Character.TYPE; break;
115 case 'S': type = Short.TYPE; break;
116 case 'I': type = Integer.TYPE; break;
117 case 'J': type = Long.TYPE; break;
118 case 'F': type = Float.TYPE; break;
119 case 'D': type = Double.TYPE; break;
120 case 'L':
121 case '[': type = Object.class; break;
122 default: throw new IllegalArgumentException("illegal signature");
123 }
124 }
125
126 /**
127 * Creates an ObjectStreamField representing the given field with the
128 * specified unshared setting. For compatibility with the behavior of
129 * earlier serialization implementations, a "showType" parameter is
130 * necessary to govern whether or not a getType() call on this
131 * ObjectStreamField (if non-primitive) will return Object.class (as
132 * opposed to a more specific reference type).
133 */
134 ObjectStreamField(Field field, boolean unshared, boolean showType) {
135 this.field = field;
136 this.unshared = unshared;
137 name = field.getName();
138 Class<?> ftype = field.getType();
139 if (showType || ftype.isPrimitive()) {
140 type = ftype;
141 signature = null; // will be lazily obtained from type
142 } else {
143 type = Object.class;
144 signature = ftype.getJvmTypeSignature();
145 }
146 }
147
148 /**
149 * Get the name of this field.
150 *
151 * @return a <code>String</code> representing the name of the serializable
152 * field
153 */
154 public String getName() {
155 return name;
156 }
157
158 /**
159 * Get the type of the field. If the type is non-primitive and this
160 * <code>ObjectStreamField</code> was obtained from a deserialized {@link
161 * ObjectStreamClass} instance, then <code>Object.class</code> is returned.
162 * Otherwise, the <code>Class</code> object for the type of the field is
163 * returned.
164 *
165 * @return a <code>Class</code> object representing the type of the
166 * serializable field
167 */
168 @CallerSensitive
169 public Class<?> getType() {
170 if (System.getSecurityManager() != null) {
171 Class<?> caller = Reflection.getCallerClass();
172 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), type.getClassLoader())) {
173 ReflectUtil.checkPackageAccess(type);
174 }
175 }
176 return type;
177 }
178
179 /**
180 * Returns character encoding of field type. The encoding is as follows:
181 * <blockquote><pre>
182 * B byte
183 * C char
184 * D double
185 * F float
186 * I int
187 * J long
188 * L class or interface
189 * S short
190 * Z boolean
191 * [ array
192 * </pre></blockquote>
193 *
194 * @return the typecode of the serializable field
195 */
196 // REMIND: deprecate?
197 public char getTypeCode() {
198 return getSignature().charAt(0);
199 }
200
201 /**
202 * Return the JVM type signature.
203 *
204 * @return null if this field has a primitive type.
205 */
206 // REMIND: deprecate?
207 public String getTypeString() {
208 return isPrimitive() ? null : getSignature();
209 }
210
211 /**
212 * Offset of field within instance data.
213 *
214 * @return the offset of this field
215 * @see #setOffset
216 */
217 // REMIND: deprecate?
218 public int getOffset() {
219 return offset;
220 }
221
222 /**
223 * Offset within instance data.
224 *
225 * @param offset the offset of the field
226 * @see #getOffset
227 */
228 // REMIND: deprecate?
229 protected void setOffset(int offset) {
230 this.offset = offset;
231 }
232
233 /**
234 * Return true if this field has a primitive type.
235 *
236 * @return true if and only if this field corresponds to a primitive type
237 */
238 // REMIND: deprecate?
239 public boolean isPrimitive() {
240 char tcode = getSignature().charAt(0);
241 return ((tcode != 'L') && (tcode != '['));
242 }
243
244 /**
245 * Returns boolean value indicating whether or not the serializable field
246 * represented by this ObjectStreamField instance is unshared.
247 *
248 * @return {@code true} if this field is unshared
249 *
250 * @since 1.4
251 */
252 public boolean isUnshared() {
253 return unshared;
254 }
255
256 /**
257 * Compare this field with another <code>ObjectStreamField</code>. Return
258 * -1 if this is smaller, 0 if equal, 1 if greater. Types that are
259 * primitives are "smaller" than object types. If equal, the field names
260 * are compared.
261 */
262 // REMIND: deprecate?
263 public int compareTo(Object obj) {
264 ObjectStreamField other = (ObjectStreamField) obj;
265 boolean isPrim = isPrimitive();
266 if (isPrim != other.isPrimitive()) {
267 return isPrim ? -1 : 1;
268 }
269 return name.compareTo(other.name);
270 }
271
272 /**
273 * Return a string that describes this field.
274 */
275 public String toString() {
276 return getSignature() + ' ' + name;
277 }
278
279 /**
280 * Returns field represented by this ObjectStreamField, or null if
281 * ObjectStreamField is not associated with an actual field.
282 */
283 Field getField() {
284 return field;
285 }
286
287 /**
288 * Returns JVM type signature of field (similar to getTypeString, except
289 * that signature strings are returned for primitive fields as well).
290 */
291 String getSignature() {
292 return signature == null ? type.getJvmTypeSignature() : signature;
293 }
294 }