378 lines
11 KiB
Java
378 lines
11 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;
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import java.lang.annotation.Annotation;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.util.Arrays;
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import org.apache.commons.lang3.builder.ToStringBuilder;
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import org.apache.commons.lang3.builder.ToStringStyle;
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import net.lax1dude.eaglercraft.v1_8.HString;
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/**
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* <p>
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* Helper methods for working with {@link Annotation} instances.
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* </p>
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*
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* <p>
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* This class contains various utility methods that make working with
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* annotations simpler.
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* </p>
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*
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* <p>
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* {@link Annotation} instances are always proxy objects; unfortunately dynamic
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* proxies cannot be depended upon to know how to implement certain methods in
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* the same manner as would be done by "natural" {@link Annotation}s. The
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* methods presented in this class can be used to avoid that possibility. It is
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* of course also possible for dynamic proxies to actually delegate their e.g.
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* {@link Annotation#equals(Object)}/{@link Annotation#hashCode()}/
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* {@link Annotation#toString()} implementations to {@link AnnotationUtils}.
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* </p>
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*
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* <p>
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* #ThreadSafe#
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* </p>
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*
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* @since 3.0
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*/
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public class AnnotationUtils {
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/**
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* A style that prints annotations as recommended.
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*/
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private static final ToStringStyle TO_STRING_STYLE = new ToStringStyle() {
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/** Serialization version */
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private static final long serialVersionUID = 1L;
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{
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setDefaultFullDetail(true);
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setArrayContentDetail(true);
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setUseClassName(true);
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setUseShortClassName(true);
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setUseIdentityHashCode(false);
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setContentStart("(");
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setContentEnd(")");
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setFieldSeparator(", ");
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setArrayStart("[");
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setArrayEnd("]");
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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protected String getShortClassName(final Class<?> cls) {
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return cls.getSimpleName();
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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protected void appendDetail(final StringBuffer buffer, final String fieldName, Object value) {
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if (value instanceof Annotation) {
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value = AnnotationUtils.toString((Annotation) value);
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}
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super.appendDetail(buffer, fieldName, value);
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}
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};
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/**
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* <p>
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* {@code AnnotationUtils} instances should NOT be constructed in standard
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* programming. Instead, the class should be used statically.
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* </p>
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*
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* <p>
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* This constructor is public to permit tools that require a JavaBean instance
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* to operate.
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* </p>
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*/
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public AnnotationUtils() {
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}
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// -----------------------------------------------------------------------
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/**
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* <p>
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* Checks if two annotations are equal using the criteria for equality presented
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* in the {@link Annotation#equals(Object)} API docs.
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* </p>
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*
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* @param a1 the first Annotation to compare, {@code null} returns {@code false}
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* unless both are {@code null}
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* @param a2 the second Annotation to compare, {@code null} returns
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* {@code false} unless both are {@code null}
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* @return {@code true} if the two annotations are {@code equal} or both
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* {@code null}
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*/
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public static boolean equals(final Annotation a1, final Annotation a2) {
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if (a1 == a2) {
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return true;
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}
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if (a1 == null || a2 == null) {
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return false;
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}
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final Class<? extends Annotation> type1 = a1.annotationType();
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final Class<? extends Annotation> type2 = a2.annotationType();
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Validate.notNull(type1, "Annotation %s with null annotationType()", a1);
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Validate.notNull(type2, "Annotation %s with null annotationType()", a2);
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if (!type1.equals(type2)) {
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return false;
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}
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try {
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for (final Method m : type1.getDeclaredMethods()) {
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if (m.getParameterTypes().length == 0 && isValidAnnotationMemberType(m.getReturnType())) {
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final Object v1 = m.invoke(a1);
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final Object v2 = m.invoke(a2);
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if (!memberEquals(m.getReturnType(), v1, v2)) {
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return false;
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}
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}
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}
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} catch (final IllegalAccessException | InvocationTargetException ex) {
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return false;
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}
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return true;
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}
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/**
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* <p>
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* Generate a hash code for the given annotation using the algorithm presented
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* in the {@link Annotation#hashCode()} API docs.
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* </p>
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*
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* @param a the Annotation for a hash code calculation is desired, not
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* {@code null}
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* @return the calculated hash code
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* @throws RuntimeException if an {@code Exception} is encountered during
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* annotation member access
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* @throws IllegalStateException if an annotation method invocation returns
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* {@code null}
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*/
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public static int hashCode(final Annotation a) {
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int result = 0;
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final Class<? extends Annotation> type = a.annotationType();
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for (final Method m : type.getDeclaredMethods()) {
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try {
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final Object value = m.invoke(a);
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if (value == null) {
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throw new IllegalStateException(HString.format("Annotation method %s returned null", m));
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}
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result += hashMember(m.getName(), value);
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} catch (final RuntimeException ex) {
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throw ex;
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} catch (final Exception ex) {
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throw new RuntimeException(ex);
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}
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}
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return result;
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}
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/**
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* <p>
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* Generate a string representation of an Annotation, as suggested by
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* {@link Annotation#toString()}.
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* </p>
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*
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* @param a the annotation of which a string representation is desired
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* @return the standard string representation of an annotation, not {@code null}
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*/
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public static String toString(final Annotation a) {
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final ToStringBuilder builder = new ToStringBuilder(a, TO_STRING_STYLE);
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for (final Method m : a.annotationType().getDeclaredMethods()) {
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if (m.getParameterTypes().length > 0) {
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continue; // wtf?
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}
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try {
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builder.append(m.getName(), m.invoke(a));
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} catch (final RuntimeException ex) {
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throw ex;
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} catch (final Exception ex) {
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throw new RuntimeException(ex);
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}
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}
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return builder.build();
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}
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/**
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* <p>
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* Checks if the specified type is permitted as an annotation member.
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* </p>
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*
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* <p>
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* The Java language specification only permits certain types to be used in
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* annotations. These include {@link String}, {@link Class}, primitive types,
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* {@link Annotation}, {@link Enum}, and single-dimensional arrays of these
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* types.
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* </p>
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*
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* @param type the type to check, {@code null}
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* @return {@code true} if the type is a valid type to use in an annotation
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*/
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public static boolean isValidAnnotationMemberType(Class<?> type) {
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if (type == null) {
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return false;
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}
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if (type.isArray()) {
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type = type.getComponentType();
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}
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return type.isPrimitive() || type.isEnum() || type.isAnnotation() || String.class.equals(type)
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|| Class.class.equals(type);
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}
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// besides modularity, this has the advantage of autoboxing primitives:
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/**
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* Helper method for generating a hash code for a member of an annotation.
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*
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* @param name the name of the member
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* @param value the value of the member
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* @return a hash code for this member
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*/
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private static int hashMember(final String name, final Object value) {
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final int part1 = name.hashCode() * 127;
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if (value.getClass().isArray()) {
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return part1 ^ arrayMemberHash(value.getClass().getComponentType(), value);
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}
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if (value instanceof Annotation) {
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return part1 ^ hashCode((Annotation) value);
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}
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return part1 ^ value.hashCode();
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}
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/**
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* Helper method for checking whether two objects of the given type are equal.
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* This method is used to compare the parameters of two annotation instances.
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*
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* @param type the type of the objects to be compared
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* @param o1 the first object
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* @param o2 the second object
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* @return a flag whether these objects are equal
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*/
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private static boolean memberEquals(final Class<?> type, final Object o1, final Object o2) {
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if (o1 == o2) {
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return true;
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}
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if (o1 == null || o2 == null) {
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return false;
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}
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if (type.isArray()) {
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return arrayMemberEquals(type.getComponentType(), o1, o2);
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}
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if (type.isAnnotation()) {
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return equals((Annotation) o1, (Annotation) o2);
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}
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return o1.equals(o2);
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}
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/**
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* Helper method for comparing two objects of an array type.
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*
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* @param componentType the component type of the array
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* @param o1 the first object
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* @param o2 the second object
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* @return a flag whether these objects are equal
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*/
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private static boolean arrayMemberEquals(final Class<?> componentType, final Object o1, final Object o2) {
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if (componentType.isAnnotation()) {
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return annotationArrayMemberEquals((Annotation[]) o1, (Annotation[]) o2);
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}
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if (componentType.equals(Byte.TYPE)) {
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return Arrays.equals((byte[]) o1, (byte[]) o2);
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}
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if (componentType.equals(Short.TYPE)) {
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return Arrays.equals((short[]) o1, (short[]) o2);
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}
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if (componentType.equals(Integer.TYPE)) {
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return Arrays.equals((int[]) o1, (int[]) o2);
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}
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if (componentType.equals(Character.TYPE)) {
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return Arrays.equals((char[]) o1, (char[]) o2);
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}
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if (componentType.equals(Long.TYPE)) {
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return Arrays.equals((long[]) o1, (long[]) o2);
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}
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if (componentType.equals(Float.TYPE)) {
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return Arrays.equals((float[]) o1, (float[]) o2);
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}
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if (componentType.equals(Double.TYPE)) {
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return Arrays.equals((double[]) o1, (double[]) o2);
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}
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if (componentType.equals(Boolean.TYPE)) {
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return Arrays.equals((boolean[]) o1, (boolean[]) o2);
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}
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return Arrays.equals((Object[]) o1, (Object[]) o2);
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}
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/**
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* Helper method for comparing two arrays of annotations.
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*
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* @param a1 the first array
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* @param a2 the second array
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* @return a flag whether these arrays are equal
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*/
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private static boolean annotationArrayMemberEquals(final Annotation[] a1, final Annotation[] a2) {
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if (a1.length != a2.length) {
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return false;
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}
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for (int i = 0; i < a1.length; i++) {
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if (!equals(a1[i], a2[i])) {
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return false;
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}
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}
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return true;
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}
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/**
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* Helper method for generating a hash code for an array.
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*
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* @param componentType the component type of the array
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* @param o the array
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* @return a hash code for the specified array
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*/
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private static int arrayMemberHash(final Class<?> componentType, final Object o) {
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if (componentType.equals(Byte.TYPE)) {
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return Arrays.hashCode((byte[]) o);
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}
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if (componentType.equals(Short.TYPE)) {
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return Arrays.hashCode((short[]) o);
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}
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if (componentType.equals(Integer.TYPE)) {
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return Arrays.hashCode((int[]) o);
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}
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if (componentType.equals(Character.TYPE)) {
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return Arrays.hashCode((char[]) o);
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}
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if (componentType.equals(Long.TYPE)) {
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return Arrays.hashCode((long[]) o);
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}
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if (componentType.equals(Float.TYPE)) {
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return Arrays.hashCode((float[]) o);
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}
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if (componentType.equals(Double.TYPE)) {
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return Arrays.hashCode((double[]) o);
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}
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if (componentType.equals(Boolean.TYPE)) {
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return Arrays.hashCode((boolean[]) o);
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}
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return Arrays.hashCode((Object[]) o);
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}
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}
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