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 *      https://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<Person> {
041 *   String name;
042 *   int age;
043 *   boolean smoker;
044 *   ...
045 *
046 *   public DiffResult<Person> diff(Person obj) {
047 *     // No need for null check, as NullPointerException correct if obj is null
048 *     return 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()  // -> ReflectionDiffBuilder
056 *       .build(); // -> DiffResult
057 *   }
058 * }
059 * }</pre>
060 *
061 * <p>
062 * The {@link ToStringStyle} passed to the constructor is embedded in the returned {@link DiffResult} and influences the style of the
063 * {@code DiffResult.toString()} method. This style choice can be overridden by calling {@link DiffResult#toString(ToStringStyle)}.
064 * </p>
065 * <p>
066 * See {@link DiffBuilder} for a non-reflection based version of this class.
067 * </p>
068 *
069 * @param <T> type of the left and right object to diff.
070 * @see Diffable
071 * @see Diff
072 * @see DiffResult
073 * @see ToStringStyle
074 * @see DiffBuilder
075 * @since 3.6
076 */
077public class ReflectionDiffBuilder<T> implements Builder<DiffResult<T>> {
078
079    /**
080     * Constructs a new instance.
081     *
082     * @param <T> type of the left and right object.
083     * @since 3.15.0
084     */
085    public static final class Builder<T> {
086
087        private String[] excludeFieldNames = ArrayUtils.EMPTY_STRING_ARRAY;
088        private DiffBuilder<T> diffBuilder;
089
090        /**
091         * Constructs a new instance.
092         */
093        public Builder() {
094            // empty
095        }
096
097        /**
098         * Builds a new configured {@link ReflectionDiffBuilder}.
099         *
100         * @return a new configured {@link ReflectionDiffBuilder}.
101         */
102        public ReflectionDiffBuilder<T> build() {
103            return new ReflectionDiffBuilder<>(diffBuilder, excludeFieldNames);
104        }
105
106        /**
107         * Sets the DiffBuilder.
108         *
109         * @param diffBuilder the DiffBuilder.
110         * @return {@code this} instance.
111         */
112        public Builder<T> setDiffBuilder(final DiffBuilder<T> diffBuilder) {
113            this.diffBuilder = diffBuilder;
114            return this;
115        }
116
117        /**
118         * Sets field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
119         *
120         * @param excludeFieldNames field names to exclude.
121         * @return {@code this} instance.
122         */
123        public Builder<T> setExcludeFieldNames(final String... excludeFieldNames) {
124            this.excludeFieldNames = toExcludeFieldNames(excludeFieldNames);
125            return this;
126        }
127
128    }
129
130    /**
131     * Constructs a new {@link Builder}.
132     *
133     * @param <T> type of the left and right object.
134     * @return a new {@link Builder}.
135     * @since 3.15.0
136     */
137    public static <T> Builder<T> builder() {
138        return new Builder<>();
139    }
140
141    private static String[] toExcludeFieldNames(final String[] excludeFieldNames) {
142        if (excludeFieldNames == null) {
143            return ArrayUtils.EMPTY_STRING_ARRAY;
144        }
145        // clone and remove nulls
146        return ArraySorter.sort(ReflectionToStringBuilder.toNoNullStringArray(excludeFieldNames));
147    }
148
149    private final DiffBuilder<T> diffBuilder;
150
151    /**
152     * Field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
153     */
154    private String[] excludeFieldNames;
155
156    private ReflectionDiffBuilder(final DiffBuilder<T> diffBuilder, final String[] excludeFieldNames) {
157        this.diffBuilder = diffBuilder;
158        this.excludeFieldNames = excludeFieldNames;
159    }
160
161    /**
162     * Constructs a builder for the specified objects with the specified style.
163     *
164     * <p>
165     * 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
166     * {@link DiffResult} when {@link #build()} is executed.
167     * </p>
168     *
169     * @param left  {@code this} object.
170     * @param right the object to diff against.
171     * @param style the style will use when outputting the objects, {@code null} uses the default
172     * @throws IllegalArgumentException if {@code left} or {@code right} is {@code null}.
173     * @deprecated Use {@link Builder}.
174     */
175    @Deprecated
176    public ReflectionDiffBuilder(final T left, final T right, final ToStringStyle style) {
177        this(DiffBuilder.<T>builder().setLeft(left).setRight(right).setStyle(style).build(), null);
178    }
179
180    private boolean accept(final Field field) {
181        if (field.getName().indexOf(ClassUtils.INNER_CLASS_SEPARATOR_CHAR) != -1) {
182            return false;
183        }
184        if (Modifier.isTransient(field.getModifiers())) {
185            return false;
186        }
187        if (Modifier.isStatic(field.getModifiers())) {
188            return false;
189        }
190        if (this.excludeFieldNames != null && Arrays.binarySearch(this.excludeFieldNames, field.getName()) >= 0) {
191            // Reject fields from the getExcludeFieldNames list.
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 this.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
254     *            the field to use
255     * @param target
256     *            the object to call on, may be {@code null} for {@code static} fields
257     * @return the field value
258     * @throws NullPointerException
259     *             if the field is {@code null}
260     * @throws IllegalAccessException
261     *             if the field is not made accessible
262     * @throws SecurityException if an underlying accessible object's method denies the request.
263     * @see SecurityManager#checkPermission
264     */
265    private Object readField(final Field field, final Object target) throws IllegalAccessException {
266        return FieldUtils.readField(field, target, true);
267    }
268
269    /**
270     * Sets the field names to exclude.
271     *
272     * @param excludeFieldNames The field names to exclude from the diff or {@code null}.
273     * @return {@code this}
274     * @since 3.13.0
275     * @deprecated Use {@link Builder#setExcludeFieldNames(String[])}.
276     */
277    @Deprecated
278    public ReflectionDiffBuilder<T> setExcludeFieldNames(final String... excludeFieldNames) {
279        this.excludeFieldNames = toExcludeFieldNames(excludeFieldNames);
280        return this;
281    }
282
283}