- 001
/* - 002
* @(#)ObjectStreamField.java 1.47 06/04/07 - 003 *
- 004 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
- 005 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- 006
*/ - 007
- 008package java.io;
- 009
- 010import java.lang.reflect.Field;
- 011
- 012/**
- 013 * A description of a Serializable field from a Serializable class. An array
- 014 * of ObjectStreamFields is used to declare the Serializable fields of a class.
- 015 *
- 016 * @author Mike Warres
- 017 * @author Roger Riggs
- 018 * @version 1.47, 06/04/07
- 019 * @see ObjectStreamClass
- 020 * @since 1.2
- 021 */
- 022public class ObjectStreamField
- 023 implements Comparable<Object>
- 024{
- 025
- 026 /** field name */
- 027 private final String name;
- 028 /** canonical JVM signature of field type */
- 029 private final String signature;
- 030 /** field type (Object.class if unknown non-primitive type) */
- 031 private final Class type;
- 032 /** whether or not to (de)serialize field values as unshared */
- 033 private final boolean unshared;
- 034 /** corresponding reflective field object, if any */
- 035 private final Field field;
- 036 /** offset of field value in enclosing field group */
- 037 private int offset = 0;
- 038
- 039 /**
- 040 * Create a Serializable field with the specified type. This field should
- 041 * be documented with a <code>serialField</code> tag.
- 042 *
- 043 * @param name the name of the serializable field
- 044 * @param type the <code>Class</code> object of the serializable field
- 045 */
- 046 public ObjectStreamField(String name, Class<?> type) {
- 047 this(name, type, false);
- 048 }
- 049
- 050 /**
- 051 * Creates an ObjectStreamField representing a serializable field with the
- 052 * given name and type. If unshared is false, values of the represented
- 053 * field are serialized and deserialized in the default manner--if the
- 054 * field is non-primitive, object values are serialized and deserialized as
- 055 * if they had been written and read by calls to writeObject and
- 056 * readObject. If unshared is true, values of the represented field are
- 057 * serialized and deserialized as if they had been written and read by
- 058 * calls to writeUnshared and readUnshared.
- 059 *
- 060 * @param name field name
- 061 * @param type field type
- 062 * @param unshared if false, write/read field values in the same manner
- 063 * as writeObject/readObject; if true, write/read in the same
- 064 * manner as writeUnshared/readUnshared
- 065 * @since 1.4
- 066 */
- 067 public ObjectStreamField(String name, Class<?> type, boolean unshared) {
- 068 if (name == null) {
- 069 throw new NullPointerException();
- 070 }
- 071 this.name = name;
- 072 this.type = type;
- 073 this.unshared = unshared;
- 074 signature = ObjectStreamClass.getClassSignature(type).intern();
- 075 field = null;
- 076 }
- 077
- 078 /**
- 079 * Creates an ObjectStreamField representing a field with the given name,
- 080 * signature and unshared setting.
- 081 */
- 082 ObjectStreamField(String name, String signature, boolean unshared) {
- 083 if (name == null) {
- 084 throw new NullPointerException();
- 085 }
- 086 this.name = name;
- 087 this.signature = signature.intern();
- 088 this.unshared = unshared;
- 089 field = null;
- 090
- 091 switch (signature.charAt(0)) {
- 092 case 'Z': type = Boolean.TYPE; break;
- 093 case 'B': type = Byte.TYPE; break;
- 094 case 'C': type = Character.TYPE; break;
- 095 case 'S': type = Short.TYPE; break;
- 096 case 'I': type = Integer.TYPE; break;
- 097 case 'J': type = Long.TYPE; break;
- 098 case 'F': type = Float.TYPE; break;
- 099 case 'D': type = Double.TYPE; break;
- 100 case 'L':
- 101 case '[': type = Object.class; break;
- 102 default: throw new IllegalArgumentException("illegal signature");
- 103 }
- 104 }
- 105
- 106 /**
- 107 * Creates an ObjectStreamField representing the given field with the
- 108 * specified unshared setting. For compatibility with the behavior of
- 109 * earlier serialization implementations, a "showType" parameter is
- 110 * necessary to govern whether or not a getType() call on this
- 111 * ObjectStreamField (if non-primitive) will return Object.class (as
- 112 * opposed to a more specific reference type).
- 113 */
- 114 ObjectStreamField(Field field, boolean unshared, boolean showType) {
- 115 this.field = field;
- 116 this.unshared = unshared;
- 117 name = field.getName();
- 118 Class ftype = field.getType();
- 119 type = (showType || ftype.isPrimitive()) ? ftype : Object.class;
- 120 signature = ObjectStreamClass.getClassSignature(ftype).intern();
- 121 }
- 122
- 123 /**
- 124 * Get the name of this field.
- 125 *
- 126 * @return a <code>String</code> representing the name of the serializable
- 127 * field
- 128 */
- 129 public String getName() {
- 130 return name;
- 131 }
- 132
- 133 /**
- 134 * Get the type of the field. If the type is non-primitive and this
- 135 * <code>ObjectStreamField</code> was obtained from a deserialized {@link
- 136 * ObjectStreamClass} instance, then <code>Object.class</code> is returned.
- 137 * Otherwise, the <code>Class</code> object for the type of the field is
- 138 * returned.
- 139 *
- 140 * @return a <code>Class</code> object representing the type of the
- 141 * serializable field
- 142 */
- 143 public Class<?> getType() {
- 144 return type;
- 145 }
- 146
- 147 /**
- 148 * Returns character encoding of field type. The encoding is as follows:
- 149 * <blockquote><pre>
- 150 * B byte
- 151 * C char
- 152 * D double
- 153 * F float
- 154 * I int
- 155 * J long
- 156 * L class or interface
- 157 * S short
- 158 * Z boolean
- 159 * [ array
- 160 * </pre></blockquote>
- 161 *
- 162 * @return the typecode of the serializable field
- 163 */
- 164 // REMIND: deprecate?
- 165 public char getTypeCode() {
- 166 return signature.charAt(0);
- 167 }
- 168
- 169 /**
- 170 * Return the JVM type signature.
- 171 *
- 172 * @return null if this field has a primitive type.
- 173 */
- 174 // REMIND: deprecate?
- 175 public String getTypeString() {
- 176 return isPrimitive() ? null : signature;
- 177 }
- 178
- 179 /**
- 180 * Offset of field within instance data.
- 181 *
- 182 * @return the offset of this field
- 183 * @see #setOffset
- 184 */
- 185 // REMIND: deprecate?
- 186 public int getOffset() {
- 187 return offset;
- 188 }
- 189
- 190 /**
- 191 * Offset within instance data.
- 192 *
- 193 * @param offset the offset of the field
- 194 * @see #getOffset
- 195 */
- 196 // REMIND: deprecate?
- 197 protected void setOffset(int offset) {
- 198 this.offset = offset;
- 199 }
- 200
- 201 /**
- 202 * Return true if this field has a primitive type.
- 203 *
- 204 * @return true if and only if this field corresponds to a primitive type
- 205 */
- 206 // REMIND: deprecate?
- 207 public boolean isPrimitive() {
- 208 char tcode = signature.charAt(0);
- 209 return ((tcode != 'L') && (tcode != '['));
- 210 }
- 211
- 212 /**
- 213 * Returns boolean value indicating whether or not the serializable field
- 214 * represented by this ObjectStreamField instance is unshared.
- 215 *
- 216 * @since 1.4
- 217 */
- 218 public boolean isUnshared() {
- 219 return unshared;
- 220 }
- 221
- 222 /**
- 223 * Compare this field with another <code>ObjectStreamField</code>. Return
- 224 * -1 if this is smaller, 0 if equal, 1 if greater. Types that are
- 225 * primitives are "smaller" than object types. If equal, the field names
- 226 * are compared.
- 227 */
- 228 // REMIND: deprecate?
- 229 public int compareTo(Object obj) {
- 230 ObjectStreamField other = (ObjectStreamField) obj;
- 231 boolean isPrim = isPrimitive();
- 232 if (isPrim != other.isPrimitive()) {
- 233 return isPrim ? -1 : 1;
- 234 }
- 235 return name.compareTo(other.name);
- 236 }
- 237
- 238 /**
- 239 * Return a string that describes this field.
- 240 */
- 241 public String toString() {
- 242 return signature + ' ' + name;
- 243 }
- 244
- 245 /**
- 246 * Returns field represented by this ObjectStreamField, or null if
- 247 * ObjectStreamField is not associated with an actual field.
- 248 */
- 249 Field getField() {
- 250 return field;
- 251 }
- 252
- 253 /**
- 254 * Returns JVM type signature of field (similar to getTypeString, except
- 255 * that signature strings are returned for primitive fields as well).
- 256 */
- 257 String getSignature() {
- 258 return signature;
- 259 }
- 260}
