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 volatile 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;
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 * Returns JVM type signature for given primitive.
128 */
129 private static String getPrimitiveSignature(Class<?> cl) {
130 if (cl == Integer.TYPE)
131 return "I";
132 else if (cl == Byte.TYPE)
133 return "B";
134 else if (cl == Long.TYPE)
135 return "J";
136 else if (cl == Float.TYPE)
137 return "F";
138 else if (cl == Double.TYPE)
139 return "D";
140 else if (cl == Short.TYPE)
141 return "S";
142 else if (cl == Character.TYPE)
143 return "C";
144 else if (cl == Boolean.TYPE)
145 return "Z";
146 else if (cl == Void.TYPE)
147 return "V";
148 else
149 throw new InternalError();
150 }
151
152 /**
153 * Returns JVM type signature for given class.
154 */
155 static String getClassSignature(Class<?> cl) {
156 if (cl.isPrimitive()) {
157 return getPrimitiveSignature(cl);
158 } else {
159 return appendClassSignature(new StringBuilder(), cl).toString();
160 }
161 }
162
163 static StringBuilder appendClassSignature(StringBuilder sbuf, Class<?> cl) {
164 while (cl.isArray()) {
165 sbuf.append('[');
166 cl = cl.getComponentType();
167 }
168
169 if (cl.isPrimitive()) {
170 sbuf.append(getPrimitiveSignature(cl));
171 } else {
172 sbuf.append('L').append(cl.getName().replace('.', '/')).append(';');
173 }
174
175 return sbuf;
176 }
177
178 /**
179 * Creates an ObjectStreamField representing the given field with the
180 * specified unshared setting. For compatibility with the behavior of
181 * earlier serialization implementations, a "showType" parameter is
182 * necessary to govern whether or not a getType() call on this
183 * ObjectStreamField (if non-primitive) will return Object.class (as
184 * opposed to a more specific reference type).
185 */
186 ObjectStreamField(Field field, boolean unshared, boolean showType) {
187 this.field = field;
188 this.unshared = unshared;
189 name = field.getName();
190 Class<?> ftype = field.getType();
191 type = (showType || ftype.isPrimitive()) ? ftype : Object.class;
192 signature = getClassSignature(ftype).intern();
193 }
194
195 /**
196 * Get the name of this field.
197 *
198 * @return a <code>String</code> representing the name of the serializable
199 * field
200 */
201 public String getName() {
202 return name;
203 }
204
205 /**
206 * Get the type of the field. If the type is non-primitive and this
207 * <code>ObjectStreamField</code> was obtained from a deserialized {@link
208 * ObjectStreamClass} instance, then <code>Object.class</code> is returned.
209 * Otherwise, the <code>Class</code> object for the type of the field is
210 * returned.
211 *
212 * @return a <code>Class</code> object representing the type of the
213 * serializable field
214 */
215 @CallerSensitive
216 public Class<?> getType() {
217 if (System.getSecurityManager() != null) {
218 Class<?> caller = Reflection.getCallerClass();
219 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), type.getClassLoader())) {
220 ReflectUtil.checkPackageAccess(type);
221 }
222 }
223 return type;
224 }
225
226 /**
227 * Returns character encoding of field type. The encoding is as follows:
228 * <blockquote><pre>
229 * B byte
230 * C char
231 * D double
232 * F float
233 * I int
234 * J long
235 * L class or interface
236 * S short
237 * Z boolean
238 * [ array
239 * </pre></blockquote>
240 *
241 * @return the typecode of the serializable field
242 */
243 // REMIND: deprecate?
244 public char getTypeCode() {
245 return getSignature().charAt(0);
246 }
247
248 /**
249 * Return the JVM type signature.
250 *
251 * @return null if this field has a primitive type.
252 */
253 // REMIND: deprecate?
254 public String getTypeString() {
255 return isPrimitive() ? null : getSignature();
256 }
257
258 /**
259 * Offset of field within instance data.
260 *
261 * @return the offset of this field
262 * @see #setOffset
263 */
264 // REMIND: deprecate?
265 public int getOffset() {
266 return offset;
267 }
268
269 /**
270 * Offset within instance data.
271 *
272 * @param offset the offset of the field
273 * @see #getOffset
274 */
275 // REMIND: deprecate?
276 protected void setOffset(int offset) {
277 this.offset = offset;
278 }
279
280 /**
281 * Return true if this field has a primitive type.
282 *
283 * @return true if and only if this field corresponds to a primitive type
284 */
285 // REMIND: deprecate?
286 public boolean isPrimitive() {
287 char tcode = getTypeCode();
288 return ((tcode != 'L') && (tcode != '['));
289 }
290
291 /**
292 * Returns boolean value indicating whether or not the serializable field
293 * represented by this ObjectStreamField instance is unshared.
294 *
295 * @return {@code true} if this field is unshared
296 *
297 * @since 1.4
298 */
299 public boolean isUnshared() {
300 return unshared;
301 }
302
303 /**
304 * Compare this field with another <code>ObjectStreamField</code>. Return
305 * -1 if this is smaller, 0 if equal, 1 if greater. Types that are
306 * primitives are "smaller" than object types. If equal, the field names
307 * are compared.
308 */
309 // REMIND: deprecate?
310 public int compareTo(Object obj) {
311 ObjectStreamField other = (ObjectStreamField) obj;
312 boolean isPrim = isPrimitive();
313 if (isPrim != other.isPrimitive()) {
314 return isPrim ? -1 : 1;
315 }
316 return name.compareTo(other.name);
317 }
318
319 /**
320 * Return a string that describes this field.
321 */
322 public String toString() {
323 return signature + ' ' + name;
324 }
325
326 /**
327 * Returns field represented by this ObjectStreamField, or null if
328 * ObjectStreamField is not associated with an actual field.
329 */
330 Field getField() {
331 return field;
332 }
333
334 /**
335 * Returns JVM type signature of field (similar to getTypeString, except
336 * that signature strings are returned for primitive fields as well).
337 */
338 String getSignature() {
339 String sig = signature;
340
341 // This lazy calculation is safe since sig can be null iff one of the
342 // public constructors are used, in which case type is always
343 // initialized to the exact type we want the signature to represent.
344 if (sig == null) {
345 sig = signature = getClassSignature(type).intern();
346 }
347 return sig;
348 }
349 }