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Apache Commons Lang, a package of Java utility classes for the
classes that are in java.lang's hierarchy, or are considered to be so
standard as to justify existence in java.lang.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.lang3.builder;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import org.apache.commons.lang3.ArraySorter;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.ClassUtils;
import org.apache.commons.lang3.reflect.FieldUtils;
/**
* Assists in implementing {@link Diffable#diff(Object)} methods.
*
*
* All non-static, non-transient fields (including inherited fields)
* of the objects to diff are discovered using reflection and compared
* for differences.
*
*
*
* To use this class, write code as follows:
*
*
*
* public class Person implements Diffable<Person> {
* String name;
* int age;
* boolean smoker;
* ...
*
* public DiffResult diff(Person obj) {
* // No need for null check, as NullPointerException correct if obj is null
* return new ReflectionDiffBuilder(this, obj, ToStringStyle.SHORT_PREFIX_STYLE)
* .build();
* }
* }
*
*
*
* The {@link ToStringStyle} passed to the constructor is embedded in the
* returned {@link DiffResult} and influences the style of the
* {@code DiffResult.toString()} method. This style choice can be overridden by
* calling {@link DiffResult#toString(ToStringStyle)}.
*
*
* See {@link DiffBuilder} for a non-reflection based version of this class.
*
* @param
* type of the left and right object to diff.
* @see Diffable
* @see Diff
* @see DiffResult
* @see ToStringStyle
* @see DiffBuilder
* @since 3.6
*/
public class ReflectionDiffBuilder implements Builder> {
private final T left;
private final T right;
private final DiffBuilder diffBuilder;
/**
* Field names to exclude from output. Intended for fields like {@code "password"} or {@code "lastModificationDate"}.
*
* @since 3.13.0
*/
private String[] excludeFieldNames;
/**
* Constructs a builder for the specified objects with the specified style.
*
*
* If {@code lhs == rhs} or {@code lhs.equals(rhs)} then the builder will
* not evaluate any calls to {@code append(...)} and will return an empty
* {@link DiffResult} when {@link #build()} is executed.
*
* @param lhs
* {@code this} object
* @param rhs
* the object to diff against
* @param style
* the style will use when outputting the objects, {@code null}
* uses the default
* @throws IllegalArgumentException
* if {@code lhs} or {@code rhs} is {@code null}
*/
public ReflectionDiffBuilder(final T lhs, final T rhs, final ToStringStyle style) {
this.left = lhs;
this.right = rhs;
this.diffBuilder = new DiffBuilder<>(lhs, rhs, style);
}
/**
* Gets the field names that should be excluded from the diff.
*
* @return Returns the excludeFieldNames.
* @since 3.13.0
*/
public String[] getExcludeFieldNames() {
return this.excludeFieldNames.clone();
}
/**
* Sets the field names to exclude.
*
* @param excludeFieldNamesParam
* The field names to exclude from the diff or {@code null}.
* @return {@code this}
* @since 3.13.0
*/
public ReflectionDiffBuilder setExcludeFieldNames(final String... excludeFieldNamesParam) {
if (excludeFieldNamesParam == null) {
this.excludeFieldNames = ArrayUtils.EMPTY_STRING_ARRAY;
} else {
// clone and remove nulls
this.excludeFieldNames = ArraySorter.sort(ReflectionToStringBuilder.toNoNullStringArray(excludeFieldNamesParam));
}
return this;
}
@Override
public DiffResult build() {
if (left.equals(right)) {
return diffBuilder.build();
}
appendFields(left.getClass());
return diffBuilder.build();
}
private void appendFields(final Class clazz) {
for (final Field field : FieldUtils.getAllFields(clazz)) {
if (accept(field)) {
try {
diffBuilder.append(field.getName(), FieldUtils.readField(field, left, true), FieldUtils.readField(field, right, true));
} catch (final IllegalAccessException e) {
// this can't happen. Would get a Security exception instead
// throw a runtime exception in case the impossible happens.
throw new IllegalArgumentException("Unexpected IllegalAccessException: " + e.getMessage(), e);
}
}
}
}
private boolean accept(final Field field) {
if (field.getName().indexOf(ClassUtils.INNER_CLASS_SEPARATOR_CHAR) != -1) {
return false;
}
if (Modifier.isTransient(field.getModifiers())) {
return false;
}
if (Modifier.isStatic(field.getModifiers())) {
return false;
}
if (this.excludeFieldNames != null
&& Arrays.binarySearch(this.excludeFieldNames, field.getName()) >= 0) {
// Reject fields from the getExcludeFieldNames list.
return false;
}
return !field.isAnnotationPresent(DiffExclude.class);
}
}