| 1 | /* |
| 2 | * This file is part of JON. |
| 3 | * |
| 4 | * JON is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU Lesser General Public License as published by |
| 6 | * the Free Software Foundation; either version 3 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * JON is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU Lesser General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU Lesser General Public License |
| 15 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 16 | * |
| 17 | * Copyright 2007 Michael Doberenz |
| 18 | */ |
| 19 | package org.fuwjax.jon.type; |
| 20 | |
| 21 | import java.lang.reflect.Field; |
| 22 | import java.lang.reflect.Modifier; |
| 23 | import java.security.AccessController; |
| 24 | import java.security.PrivilegedAction; |
| 25 | |
| 26 | import org.fuwjax.jon.IndirectType; |
| 27 | import org.fuwjax.jon.ObjectAccessException; |
| 28 | import org.fuwjax.jon.Reference; |
| 29 | |
| 30 | /** |
| 31 | * An entry accessor for a field. |
| 32 | * @author michaeldoberenz |
| 33 | */ |
| 34 | public class FieldWrapper{ |
| 35 | private static final String THIS = "this"; //$NON-NLS-1$ |
| 36 | private Field field; |
| 37 | private IndirectType type; |
| 38 | |
| 39 | /** |
| 40 | * Constructs a new entry proxy for <code>field</code> of type |
| 41 | * <code>type</code>. |
| 42 | * @param field the field to wrap with this entry |
| 43 | * @param type the type of the field value |
| 44 | */ |
| 45 | public FieldWrapper(final Field field, final IndirectType type){ |
| 46 | this.field = field; |
| 47 | if(!field.isAccessible()){ |
| 48 | AccessController.doPrivileged(new AccessibleAction(field)); |
| 49 | } |
| 50 | this.type = type; |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | * Returns true if <code>field</code> should not be serialized, false |
| 55 | * otherwise. |
| 56 | * @param field the field which may be transient |
| 57 | * @return true if <code>field</code> is transient, false otherwise. |
| 58 | */ |
| 59 | public static boolean isTransient(final Field field){ |
| 60 | final int mod = field.getModifiers(); |
| 61 | return isSynthetic(field) || Modifier.isStatic(mod) || Modifier.isTransient(mod); |
| 62 | } |
| 63 | |
| 64 | private static boolean isSynthetic(final Field field){ |
| 65 | return field.isSynthetic() && !field.getName().startsWith(THIS); |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * Returns the type of this field. |
| 70 | * @return the type of this field |
| 71 | */ |
| 72 | public IndirectType getType(){ |
| 73 | return type; |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Retrieves the value of this field from <code>container</code>. |
| 78 | * @param container the object with a value for this field |
| 79 | * @return the value of the field from <code>container</code> |
| 80 | * @throws ObjectAccessException if an object relationship cannot be followed |
| 81 | */ |
| 82 | public Object getValue(final Object container) throws ObjectAccessException{ |
| 83 | try{ |
| 84 | return field.get(container); |
| 85 | }catch(IllegalArgumentException e){ |
| 86 | throw ObjectAccessException.Message.ObjectNotInstanceOfType.exception(e); |
| 87 | }catch(IllegalAccessException e){ |
| 88 | throw ObjectAccessException.Message.FieldInaccessible.exception(e); |
| 89 | } |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Returns the name of the field. |
| 94 | * @return the name of the field |
| 95 | */ |
| 96 | public String getName(){ |
| 97 | return field.getName(); |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * Creates a new {@link PrivilegedAction} that sets a supplied {@link Field} |
| 102 | * accessible. |
| 103 | * @author michaeldoberenz |
| 104 | */ |
| 105 | private static final class AccessibleAction implements PrivilegedAction<Object>{ |
| 106 | private Field field; |
| 107 | |
| 108 | /** |
| 109 | * Creates a new privileged action that sets <code>field</code> |
| 110 | * accessible. |
| 111 | * @param field the field to make accessible |
| 112 | */ |
| 113 | AccessibleAction(final Field field){ |
| 114 | this.field = field; |
| 115 | } |
| 116 | |
| 117 | public Object run(){ |
| 118 | field.setAccessible(true); |
| 119 | return null; // nothing to return |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Sets the value of this field on <code>container</code> to |
| 125 | * <code>value</code>. |
| 126 | * @param container the mutated object |
| 127 | * @param value the new value of this field on <code>container</code> |
| 128 | * @throws ObjectAccessException if an object relationship cannot be restored |
| 129 | */ |
| 130 | public void setValue(final Object container, final Object value) throws ObjectAccessException{ |
| 131 | if(value instanceof Reference){ |
| 132 | ((Reference)value).setField(field, container); |
| 133 | }else{ |
| 134 | setFieldValue(container, field, value); |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * Sets the value of <code>field</code> on <code>container</code> to |
| 140 | * <code>value</code>. |
| 141 | * @param container the mutated object |
| 142 | * @param field the field to modify |
| 143 | * @param value the new value of this field on <code>container</code> |
| 144 | * @throws ObjectAccessException if an object relationship cannot be restored |
| 145 | */ |
| 146 | public static void setFieldValue(final Object container, final Field field, final Object value) |
| 147 | throws ObjectAccessException{ |
| 148 | try{ |
| 149 | field.set(container, value); |
| 150 | }catch(IllegalArgumentException e){ |
| 151 | throw ObjectAccessException.Message.ObjectNotInstanceOfType.exception(e); |
| 152 | }catch(IllegalAccessException e){ |
| 153 | throw ObjectAccessException.Message.FieldInaccessible.exception(e); |
| 154 | } |
| 155 | } |
| 156 | } |