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 = getClassSignature(type).intern(); 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 signature.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 : signature; 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 = signature.charAt(0); 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 return signature; 340 } 341 }