001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.lang3.builder;
018
019import java.lang.reflect.Field;
020import java.lang.reflect.Modifier;
021import java.util.Arrays;
022
023import org.apache.commons.lang3.ArraySorter;
024import org.apache.commons.lang3.ArrayUtils;
025import org.apache.commons.lang3.ClassUtils;
026import org.apache.commons.lang3.reflect.FieldUtils;
027
028/**
029 * Assists in implementing {@link Diffable#diff(Object)} methods.
030 *
031 * <p>
032 * All non-static, non-transient fields (including inherited fields) of the objects to diff are discovered using reflection and compared for differences.
033 * </p>
034 *
035 * <p>
036 * To use this class, write code as follows:
037 * </p>
038 *
039 * <pre>{@code
040 * public class Person implements Diffable&lt;Person&gt; {
041 *   String name;
042 *   int age;
043 *   boolean smoker;
044 *   ...
045 *
046 *   public DiffResult diff(Person obj) {
047 *     // No need for null check, as NullPointerException correct if obj is null
048 *     return new ReflectionDiffBuilder.<Person>builder()
049 *       .setDiffBuilder(DiffBuilder.<Person>builder()
050 *           .setLeft(this)
051 *           .setRight(obj)
052 *           .setStyle(ToStringStyle.SHORT_PREFIX_STYLE)
053 *           .build())
054 *       .setExcludeFieldNames("userName", "password")
055 *       .build();
056 *   }
057 * }
058 * }</pre>
059 *
060 * <p>
061 * The {@link ToStringStyle} passed to the constructor is embedded in the returned {@link DiffResult} and influences the style of the
062 * {@code DiffResult.toString()} method. This style choice can be overridden by calling {@link DiffResult#toString(ToStringStyle)}.
063 * </p>
064 * <p>
065 * See {@link DiffBuilder} for a non-reflection based version of this class.
066 * </p>
067 *
068 * @param <T> type of the left and right object to diff.
069 * @see Diffable
070 * @see Diff
071 * @see DiffResult
072 * @see ToStringStyle
073 * @see DiffBuilder
074 * @since 3.6
075 */
076public class ReflectionDiffBuilder<T> implements Builder<DiffResult<T>> {
077
078    /**
079     * Constructs a new instance.
080     *
081     * @param <T> type of the left and right object.
082     * @since 3.15.0
083     */
084    public static final class Builder<T> {
085
086        private String[] excludeFieldNames = ArrayUtils.EMPTY_STRING_ARRAY;
087        private DiffBuilder<T> diffBuilder;
088
089        /**
090         * Builds a new configured {@link ReflectionDiffBuilder}.
091         *
092         * @return a new configured {@link ReflectionDiffBuilder}.
093         */
094        public ReflectionDiffBuilder<T> build() {
095            return new ReflectionDiffBuilder<>(diffBuilder, excludeFieldNames);
096        }
097
098        /**
099         * Sets the DiffBuilder.
100         *
101         * @param diffBuilder the DiffBuilder.
102         * @return {@code this} instance.
103         */
104        public Builder<T> setDiffBuilder(final DiffBuilder<T> diffBuilder) {
105            this.diffBuilder = diffBuilder;
106            return this;
107        }
108
109        /**
110         * Sets field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
111         *
112         * @param excludeFieldNames field names to exclude.
113         * @return {@code this} instance.
114         */
115        public Builder<T> setExcludeFieldNames(final String... excludeFieldNames) {
116            this.excludeFieldNames = toExcludeFieldNames(excludeFieldNames);
117            return this;
118        }
119
120    }
121
122    /**
123     * Constructs a new {@link Builder}.
124     *
125     * @param <T> type of the left and right object.
126     * @return a new {@link Builder}.
127     * @since 3.15.0
128     */
129    public static <T> Builder<T> builder() {
130        return new Builder<>();
131    }
132
133    private static String[] toExcludeFieldNames(final String[] excludeFieldNames) {
134        if (excludeFieldNames == null) {
135            return ArrayUtils.EMPTY_STRING_ARRAY;
136        }
137        // clone and remove nulls
138        return ArraySorter.sort(ReflectionToStringBuilder.toNoNullStringArray(excludeFieldNames));
139    }
140
141    private final DiffBuilder<T> diffBuilder;
142
143    /**
144     * Field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
145     */
146    private String[] excludeFieldNames;
147
148    private ReflectionDiffBuilder(final DiffBuilder<T> diffBuilder, final String[] excludeFieldNames) {
149        this.diffBuilder = diffBuilder;
150        this.excludeFieldNames = excludeFieldNames;
151    }
152
153    /**
154     * Constructs a builder for the specified objects with the specified style.
155     *
156     * <p>
157     * 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
158     * {@link DiffResult} when {@link #build()} is executed.
159     * </p>
160     *
161     * @param left  {@code this} object.
162     * @param right the object to diff against.
163     * @param style the style will use when outputting the objects, {@code null} uses the default
164     * @throws IllegalArgumentException if {@code left} or {@code right} is {@code null}.
165     * @deprecated Use {@link Builder}.
166     */
167    @Deprecated
168    public ReflectionDiffBuilder(final T left, final T right, final ToStringStyle style) {
169        this(DiffBuilder.<T>builder().setLeft(left).setRight(right).setStyle(style).build(), null);
170    }
171
172    private boolean accept(final Field field) {
173        if (field.getName().indexOf(ClassUtils.INNER_CLASS_SEPARATOR_CHAR) != -1) {
174            return false;
175        }
176        if (Modifier.isTransient(field.getModifiers())) {
177            return false;
178        }
179        if (Modifier.isStatic(field.getModifiers())) {
180            return false;
181        }
182        if (this.excludeFieldNames != null && Arrays.binarySearch(this.excludeFieldNames, field.getName()) >= 0) {
183            // Reject fields from the getExcludeFieldNames list.
184            return false;
185        }
186        return !field.isAnnotationPresent(DiffExclude.class);
187    }
188
189    private void appendFields(final Class<?> clazz) {
190        for (final Field field : FieldUtils.getAllFields(clazz)) {
191            if (accept(field)) {
192                try {
193                    diffBuilder.append(field.getName(), readField(field, getLeft()), readField(field, getRight()));
194                } catch (final IllegalAccessException e) {
195                    // this can't happen. Would get a Security exception instead
196                    // throw a runtime exception in case the impossible happens.
197                    throw new IllegalArgumentException("Unexpected IllegalAccessException: " + e.getMessage(), e);
198                }
199            }
200        }
201    }
202
203    @Override
204    public DiffResult<T> build() {
205        if (getLeft().equals(getRight())) {
206            return diffBuilder.build();
207        }
208
209        appendFields(getLeft().getClass());
210        return diffBuilder.build();
211    }
212
213    /**
214     * Gets the field names that should be excluded from the diff.
215     *
216     * @return Returns the excludeFieldNames.
217     * @since 3.13.0
218     */
219    public String[] getExcludeFieldNames() {
220        return this.excludeFieldNames.clone();
221    }
222
223    private T getLeft() {
224        return diffBuilder.getLeft();
225    }
226
227    private T getRight() {
228        return diffBuilder.getRight();
229    }
230
231    private Object readField(final Field field, final Object target) throws IllegalAccessException {
232        return FieldUtils.readField(field, target, true);
233    }
234
235    /**
236     * Sets the field names to exclude.
237     *
238     * @param excludeFieldNames The field names to exclude from the diff or {@code null}.
239     * @return {@code this}
240     * @since 3.13.0
241     * @deprecated Use {@link Builder#setExcludeFieldNames(String[])}.
242     */
243    @Deprecated
244    public ReflectionDiffBuilder<T> setExcludeFieldNames(final String... excludeFieldNames) {
245        this.excludeFieldNames = toExcludeFieldNames(excludeFieldNames);
246        return this;
247    }
248
249}