138 lines
4.5 KiB
Java
138 lines
4.5 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3.builder;
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import static org.apache.commons.lang3.reflect.FieldUtils.readField;
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import java.lang.reflect.Field;
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import java.lang.reflect.Modifier;
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import org.apache.commons.lang3.ClassUtils;
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import org.apache.commons.lang3.reflect.FieldUtils;
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/**
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* <p>
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* Assists in implementing {@link Diffable#diff(Object)} methods.
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* </p>
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* <p>
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* All non-static, non-transient fields (including inherited fields)
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* of the objects to diff are discovered using reflection and compared
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* for differences.
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* </p>
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*
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* <p>
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* To use this class, write code as follows:
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* </p>
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*
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* <pre>
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* public class Person implements Diffable<Person> {
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* String name;
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* int age;
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* boolean smoker;
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* ...
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*
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* public DiffResult diff(Person obj) {
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* // No need for null check, as NullPointerException correct if obj is null
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* return new ReflectionDiffBuilder(this, obj, ToStringStyle.SHORT_PREFIX_STYLE)
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* .build();
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* }
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* }
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* </pre>
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*
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* <p>
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* The {@code ToStringStyle} passed to the constructor is embedded in the
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* returned {@code DiffResult} and influences the style of the
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* {@code DiffResult.toString()} method. This style choice can be overridden by
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* calling {@link DiffResult#toString(ToStringStyle)}.
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* </p>
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* @param <T>
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* type of the left and right object to diff.
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* @see Diffable
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* @see Diff
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* @see DiffResult
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* @see ToStringStyle
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* @since 3.6
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*/
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public class ReflectionDiffBuilder<T> implements Builder<DiffResult<T>> {
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private final Object left;
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private final Object right;
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private final DiffBuilder<T> diffBuilder;
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/**
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* <p>
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* Constructs a builder for the specified objects with the specified style.
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* </p>
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*
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* <p>
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* If {@code lhs == rhs} or {@code lhs.equals(rhs)} then the builder will
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* not evaluate any calls to {@code append(...)} and will return an empty
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* {@link DiffResult} when {@link #build()} is executed.
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* </p>
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* @param lhs
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* {@code this} object
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* @param rhs
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* the object to diff against
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* @param style
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* the style will use when outputting the objects, {@code null}
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* uses the default
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* @throws IllegalArgumentException
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* if {@code lhs} or {@code rhs} is {@code null}
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*/
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public ReflectionDiffBuilder(final T lhs, final T rhs, final ToStringStyle style) {
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this.left = lhs;
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this.right = rhs;
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diffBuilder = new DiffBuilder<>(lhs, rhs, style);
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}
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@Override
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public DiffResult<T> build() {
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if (left.equals(right)) {
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return diffBuilder.build();
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}
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appendFields(left.getClass());
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return diffBuilder.build();
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}
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private void appendFields(final Class<?> clazz) {
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for (final Field field : FieldUtils.getAllFields(clazz)) {
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if (accept(field)) {
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try {
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diffBuilder.append(field.getName(), readField(field, left, true),
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readField(field, right, true));
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} catch (final IllegalAccessException ex) {
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//this can't happen. Would get a Security exception instead
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//throw a runtime exception in case the impossible happens.
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throw new InternalError("Unexpected IllegalAccessException: " + ex.getMessage());
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}
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}
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}
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}
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private boolean accept(final Field field) {
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if (field.getName().indexOf(ClassUtils.INNER_CLASS_SEPARATOR_CHAR) != -1) {
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return false;
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}
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if (Modifier.isTransient(field.getModifiers())) {
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return false;
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}
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return !Modifier.isStatic(field.getModifiers());
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}
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}
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