1 /*
2 * Copyright (c) 1996, 2013, 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 sun.invoke.util.BytecodeDescriptor;
30 import sun.reflect.CallerSensitive;
31 import sun.reflect.Reflection;
32 import sun.reflect.misc.ReflectUtil;
33
34 /**
35 * A description of a Serializable field from a Serializable class. An array
36 * of ObjectStreamFields is used to declare the Serializable fields of a class.
37 *
38 * @author Mike Warres
39 * @author Roger Riggs
40 * @see ObjectStreamClass
41 * @since 1.2
42 */
43 public class ObjectStreamField
44 implements Comparable<Object>
45 {
46
47 /** field name */
48 private final String name;
49 /** canonical JVM signature of field type */
50 private final String signature;
51 /** field type (Object.class if unknown non-primitive type) */
52 private final Class<?> type;
53 /** whether or not to (de)serialize field values as unshared */
54 private final boolean unshared;
55 /** corresponding reflective field object, if any */
56 private final Field field;
57 /** offset of field value in enclosing field group */
58 private int offset = 0;
59
60 /**
61 * Create a Serializable field with the specified type. This field should
62 * be documented with a <code>serialField</code> tag.
63 *
64 * @param name the name of the serializable field
65 * @param type the <code>Class</code> object of the serializable field
66 */
67 public ObjectStreamField(String name, Class<?> type) {
68 this(name, type, false);
69 }
70
71 /**
72 * Creates an ObjectStreamField representing a serializable field with the
73 * given name and type. If unshared is false, values of the represented
74 * field are serialized and deserialized in the default manner--if the
75 * field is non-primitive, object values are serialized and deserialized as
76 * if they had been written and read by calls to writeObject and
77 * readObject. If unshared is true, values of the represented field are
78 * serialized and deserialized as if they had been written and read by
79 * calls to writeUnshared and readUnshared.
80 *
81 * @param name field name
82 * @param type field type
83 * @param unshared if false, write/read field values in the same manner
84 * as writeObject/readObject; if true, write/read in the same
85 * manner as writeUnshared/readUnshared
86 * @since 1.4
87 */
88 public ObjectStreamField(String name, Class<?> type, boolean unshared) {
89 if (name == null) {
90 throw new NullPointerException();
91 }
92 this.name = name;
93 this.type = type;
94 this.unshared = unshared;
95 signature = BytecodeDescriptor.unparse(type).intern();
96 field = null;
97 }
98
99 /**
100 * Creates an ObjectStreamField representing a field with the given name,
101 * signature and unshared setting.
102 */
103 ObjectStreamField(String name, String signature, boolean unshared) {
104 if (name == null) {
105 throw new NullPointerException();
106 }
107 this.name = name;
108 this.signature = signature.intern();
109 this.unshared = unshared;
110 field = null;
111
112 switch (signature.charAt(0)) {
113 case 'Z': type = Boolean.TYPE; break;
114 case 'B': type = Byte.TYPE; break;
115 case 'C': type = Character.TYPE; break;
116 case 'S': type = Short.TYPE; break;
117 case 'I': type = Integer.TYPE; break;
118 case 'J': type = Long.TYPE; break;
119 case 'F': type = Float.TYPE; break;
120 case 'D': type = Double.TYPE; break;
121 case 'L':
122 case '[': type = Object.class; break;
123 default: throw new IllegalArgumentException("illegal signature");
124 }
125 }
126
127 /**
128 * Creates an ObjectStreamField representing the given field with the
129 * specified unshared setting. For compatibility with the behavior of
130 * earlier serialization implementations, a "showType" parameter is
131 * necessary to govern whether or not a getType() call on this
132 * ObjectStreamField (if non-primitive) will return Object.class (as
133 * opposed to a more specific reference type).
134 */
135 ObjectStreamField(Field field, boolean unshared, boolean showType) {
136 this.field = field;
137 this.unshared = unshared;
138 name = field.getName();
139 Class<?> ftype = field.getType();
140 type = (showType || ftype.isPrimitive()) ? ftype : Object.class;
141 signature = BytecodeDescriptor.unparse(ftype).intern();
142 }
143
144 /**
145 * Get the name of this field.
146 *
147 * @return a <code>String</code> representing the name of the serializable
148 * field
149 */
150 public String getName() {
151 return name;
152 }
153
154 /**
155 * Get the type of the field. If the type is non-primitive and this
156 * <code>ObjectStreamField</code> was obtained from a deserialized {@link
157 * ObjectStreamClass} instance, then <code>Object.class</code> is returned.
158 * Otherwise, the <code>Class</code> object for the type of the field is
159 * returned.
160 *
161 * @return a <code>Class</code> object representing the type of the
162 * serializable field
163 */
164 @CallerSensitive
165 public Class<?> getType() {
166 if (System.getSecurityManager() != null) {
167 Class<?> caller = Reflection.getCallerClass();
168 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(), type.getClassLoader())) {
169 ReflectUtil.checkPackageAccess(type);
170 }
171 }
172 return type;
173 }
174
175 /**
176 * Returns character encoding of field type. The encoding is as follows:
177 * <blockquote><pre>
178 * B byte
179 * C char
180 * D double
181 * F float
182 * I int
183 * J long
184 * L class or interface
185 * S short
186 * Z boolean
187 * [ array
188 * </pre></blockquote>
189 *
190 * @return the typecode of the serializable field
191 */
192 // REMIND: deprecate?
193 public char getTypeCode() {
194 return signature.charAt(0);
195 }
196
197 /**
198 * Return the JVM type signature.
199 *
200 * @return null if this field has a primitive type.
201 */
202 // REMIND: deprecate?
203 public String getTypeString() {
204 return isPrimitive() ? null : signature;
205 }
206
207 /**
208 * Offset of field within instance data.
209 *
210 * @return the offset of this field
211 * @see #setOffset
212 */
213 // REMIND: deprecate?
214 public int getOffset() {
215 return offset;
216 }
217
218 /**
219 * Offset within instance data.
220 *
221 * @param offset the offset of the field
222 * @see #getOffset
223 */
224 // REMIND: deprecate?
225 protected void setOffset(int offset) {
226 this.offset = offset;
227 }
228
229 /**
230 * Return true if this field has a primitive type.
231 *
232 * @return true if and only if this field corresponds to a primitive type
233 */
234 // REMIND: deprecate?
235 public boolean isPrimitive() {
236 char tcode = signature.charAt(0);
237 return ((tcode != 'L') && (tcode != '['));
238 }
239
240 /**
241 * Returns boolean value indicating whether or not the serializable field
242 * represented by this ObjectStreamField instance is unshared.
243 *
244 * @return {@code true} if this field is unshared
245 *
246 * @since 1.4
247 */
248 public boolean isUnshared() {
249 return unshared;
250 }
251
252 /**
253 * Compare this field with another <code>ObjectStreamField</code>. Return
254 * -1 if this is smaller, 0 if equal, 1 if greater. Types that are
255 * primitives are "smaller" than object types. If equal, the field names
256 * are compared.
257 */
258 // REMIND: deprecate?
259 public int compareTo(Object obj) {
260 ObjectStreamField other = (ObjectStreamField) obj;
261 boolean isPrim = isPrimitive();
262 if (isPrim != other.isPrimitive()) {
263 return isPrim ? -1 : 1;
264 }
265 return name.compareTo(other.name);
266 }
267
268 /**
269 * Return a string that describes this field.
270 */
271 public String toString() {
272 return signature + ' ' + name;
273 }
274
275 /**
276 * Returns field represented by this ObjectStreamField, or null if
277 * ObjectStreamField is not associated with an actual field.
278 */
279 Field getField() {
280 return field;
281 }
282
283 /**
284 * Returns JVM type signature of field (similar to getTypeString, except
285 * that signature strings are returned for primitive fields as well).
286 */
287 String getSignature() {
288 return signature;
289 }
290 }