1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.lang3.builder;
18
19 import java.lang.reflect.Field;
20 import java.lang.reflect.Modifier;
21 import java.util.Arrays;
22 import java.util.Objects;
23
24 import org.apache.commons.lang3.ArraySorter;
25 import org.apache.commons.lang3.ArrayUtils;
26 import org.apache.commons.lang3.ClassUtils;
27 import org.apache.commons.lang3.reflect.FieldUtils;
28
29 /**
30 * Assists in implementing {@link Diffable#diff(Object)} methods.
31 *
32 * <p>
33 * All non-static, non-transient fields (including inherited fields) of the objects to diff are discovered using reflection and compared for differences.
34 * </p>
35 *
36 * <p>
37 * To use this class, write code as follows:
38 * </p>
39 *
40 * <pre>{@code
41 * public class Person implements Diffable<Person> {
42 * String name;
43 * int age;
44 * boolean smoker;
45 * ...
46 *
47 * public DiffResult<Person> diff(Person obj) {
48 * // No need for null check, as NullPointerException correct if obj is null
49 * return ReflectionDiffBuilder.<Person>builder()
50 * .setDiffBuilder(DiffBuilder.<Person>builder()
51 * .setLeft(this)
52 * .setRight(obj)
53 * .setStyle(ToStringStyle.SHORT_PREFIX_STYLE)
54 * .build())
55 * .setExcludeFieldNames("userName", "password")
56 * .build() // -> ReflectionDiffBuilder
57 * .build(); // -> DiffResult
58 * }
59 * }
60 * }</pre>
61 *
62 * <p>
63 * The {@link ToStringStyle} passed to the constructor is embedded in the returned {@link DiffResult} and influences the style of the
64 * {@code DiffResult.toString()} method. This style choice can be overridden by calling {@link DiffResult#toString(ToStringStyle)}.
65 * </p>
66 * <p>
67 * See {@link DiffBuilder} for a non-reflection based version of this class.
68 * </p>
69 *
70 * @param <T> type of the left and right object to diff.
71 * @see Diffable
72 * @see Diff
73 * @see DiffResult
74 * @see ToStringStyle
75 * @see DiffBuilder
76 * @since 3.6
77 */
78 public class ReflectionDiffBuilder<T> implements Builder<DiffResult<T>> {
79
80 /**
81 * Constructs a new instance.
82 *
83 * @param <T> type of the left and right object.
84 * @since 3.15.0
85 */
86 public static final class Builder<T> {
87
88 private String[] excludeFieldNames = ArrayUtils.EMPTY_STRING_ARRAY;
89 private DiffBuilder<T> diffBuilder;
90
91 /**
92 * Constructs a new instance.
93 */
94 public Builder() {
95 // empty
96 }
97
98 /**
99 * Builds a new configured {@link ReflectionDiffBuilder}.
100 *
101 * @return a new configured {@link ReflectionDiffBuilder}.
102 */
103 public ReflectionDiffBuilder<T> build() {
104 return new ReflectionDiffBuilder<>(diffBuilder, excludeFieldNames);
105 }
106
107 /**
108 * Sets the DiffBuilder.
109 *
110 * @param diffBuilder the DiffBuilder.
111 * @return {@code this} instance.
112 */
113 public Builder<T> setDiffBuilder(final DiffBuilder<T> diffBuilder) {
114 this.diffBuilder = diffBuilder;
115 return this;
116 }
117
118 /**
119 * Sets field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
120 *
121 * @param excludeFieldNames field names to exclude.
122 * @return {@code this} instance.
123 */
124 public Builder<T> setExcludeFieldNames(final String... excludeFieldNames) {
125 this.excludeFieldNames = toExcludeFieldNames(excludeFieldNames);
126 return this;
127 }
128
129 }
130
131 /**
132 * Constructs a new {@link Builder}.
133 *
134 * @param <T> type of the left and right object.
135 * @return a new {@link Builder}.
136 * @since 3.15.0
137 */
138 public static <T> Builder<T> builder() {
139 return new Builder<>();
140 }
141
142 private static String[] toExcludeFieldNames(final String[] excludeFieldNames) {
143 if (excludeFieldNames == null) {
144 return ArrayUtils.EMPTY_STRING_ARRAY;
145 }
146 // clone and remove nulls
147 return ArraySorter.sort(ReflectionToStringBuilder.toNoNullStringArray(excludeFieldNames));
148 }
149
150 private final DiffBuilder<T> diffBuilder;
151
152 /**
153 * Field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
154 */
155 private String[] excludeFieldNames;
156
157 /**
158 * Constructs a new instance.
159 *
160 * @param diffBuilder a non-null DiffBuilder.
161 * @param excludeFieldNames a non-null String array.
162 * @throw NullPointerException Thrown on null input.
163 */
164 private ReflectionDiffBuilder(final DiffBuilder<T> diffBuilder, final String[] excludeFieldNames) {
165 this.diffBuilder = Objects.requireNonNull(diffBuilder, "diffBuilder");
166 this.excludeFieldNames = Objects.requireNonNull(excludeFieldNames, "excludeFieldNames");
167 }
168
169 /**
170 * Constructs a builder for the specified objects with the specified style.
171 *
172 * <p>
173 * If {@code left == right} or {@code left.equals(right)} then the builder will not evaluate any calls to {@code append(...)} and will return an empty
174 * {@link DiffResult} when {@link #build()} is executed.
175 * </p>
176 *
177 * @param left {@code this} object.
178 * @param right the object to diff against.
179 * @param style the style will use when outputting the objects, {@code null} uses the default
180 * @throws IllegalArgumentException if {@code left} or {@code right} is {@code null}.
181 * @deprecated Use {@link Builder}.
182 */
183 @Deprecated
184 public ReflectionDiffBuilder(final T left, final T right, final ToStringStyle style) {
185 this(DiffBuilder.<T>builder().setLeft(left).setRight(right).setStyle(style).build(), ArrayUtils.EMPTY_STRING_ARRAY);
186 }
187
188 private boolean accept(final Field field) {
189 if (field.getName().indexOf(ClassUtils.INNER_CLASS_SEPARATOR_CHAR) != -1 || Modifier.isTransient(field.getModifiers())
190 || Modifier.isStatic(field.getModifiers()) || Arrays.binarySearch(excludeFieldNames, field.getName()) >= 0) {
191 // Rejected.
192 return false;
193 }
194 return !field.isAnnotationPresent(DiffExclude.class);
195 }
196
197 /**
198 * Appends fields using reflection.
199 *
200 * @throws SecurityException if an underlying accessible object's method denies the request.
201 * @see SecurityManager#checkPermission
202 */
203 private void appendFields(final Class<?> clazz) {
204 for (final Field field : FieldUtils.getAllFields(clazz)) {
205 if (accept(field)) {
206 try {
207 diffBuilder.append(field.getName(), readField(field, getLeft()), readField(field, getRight()));
208 } catch (final IllegalAccessException e) {
209 // this can't happen. Would get a Security exception instead
210 // throw a runtime exception in case the impossible happens.
211 throw new IllegalArgumentException("Unexpected IllegalAccessException: " + e.getMessage(), e);
212 }
213 }
214 }
215 }
216
217 /**
218 * {@inheritDoc}
219 *
220 * @throws SecurityException if an underlying accessible object's method denies the request.
221 * @see SecurityManager#checkPermission
222 */
223 @Override
224 public DiffResult<T> build() {
225 if (getLeft().equals(getRight())) {
226 return diffBuilder.build();
227 }
228 appendFields(getLeft().getClass());
229 return diffBuilder.build();
230 }
231
232 /**
233 * Gets the field names that should be excluded from the diff.
234 *
235 * @return the excludeFieldNames.
236 * @since 3.13.0
237 */
238 public String[] getExcludeFieldNames() {
239 return excludeFieldNames.clone();
240 }
241
242 private T getLeft() {
243 return diffBuilder.getLeft();
244 }
245
246 private T getRight() {
247 return diffBuilder.getRight();
248 }
249
250 /**
251 * Reads a {@link Field}, forcing access if needed.
252 *
253 * @param field the field to use.
254 * @param target the object to call on, may be {@code null} for {@code static} fields.
255 * @return the field value.
256 * @throws NullPointerException if the field is {@code null}.
257 * @throws IllegalAccessException if the field is not made accessible.
258 * @throws SecurityException if an underlying accessible object's method denies the request.
259 * @see SecurityManager#checkPermission
260 */
261 private Object readField(final Field field, final Object target) throws IllegalAccessException {
262 return FieldUtils.readField(field, target, true);
263 }
264
265 /**
266 * Sets the field names to exclude.
267 *
268 * @param excludeFieldNames The field names to exclude from the diff or {@code null}.
269 * @return {@code this} instance.
270 * @since 3.13.0
271 * @deprecated Use {@link Builder#setExcludeFieldNames(String[])}.
272 */
273 @Deprecated
274 public ReflectionDiffBuilder<T> setExcludeFieldNames(final String... excludeFieldNames) {
275 this.excludeFieldNames = toExcludeFieldNames(excludeFieldNames);
276 return this;
277 }
278
279 }