001/*
002 * Copyright 2012-2017 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.boot.validation;
018
019import java.util.Collections;
020import java.util.LinkedHashSet;
021import java.util.Set;
022
023import javax.validation.MessageInterpolator;
024import javax.validation.Validation;
025import javax.validation.ValidationException;
026
027import org.springframework.beans.BeanUtils;
028import org.springframework.beans.BeansException;
029import org.springframework.beans.factory.ObjectFactory;
030import org.springframework.util.ClassUtils;
031
032/**
033 * {@link ObjectFactory} that can be used to create a {@link MessageInterpolator}.
034 * Attempts to pick the most appropriate {@link MessageInterpolator} based on the
035 * classpath.
036 *
037 * @author Phillip Webb
038 */
039public class MessageInterpolatorFactory implements ObjectFactory<MessageInterpolator> {
040
041        private static final Set<String> FALLBACKS;
042
043        static {
044                Set<String> fallbacks = new LinkedHashSet<>();
045                fallbacks.add("org.hibernate.validator.messageinterpolation"
046                                + ".ParameterMessageInterpolator");
047                FALLBACKS = Collections.unmodifiableSet(fallbacks);
048        }
049
050        @Override
051        public MessageInterpolator getObject() throws BeansException {
052                try {
053                        return Validation.byDefaultProvider().configure()
054                                        .getDefaultMessageInterpolator();
055                }
056                catch (ValidationException ex) {
057                        MessageInterpolator fallback = getFallback();
058                        if (fallback != null) {
059                                return fallback;
060                        }
061                        throw ex;
062                }
063        }
064
065        private MessageInterpolator getFallback() {
066                for (String fallback : FALLBACKS) {
067                        try {
068                                return getFallback(fallback);
069                        }
070                        catch (Exception ex) {
071                                // Swallow an continue
072                        }
073                }
074                return null;
075        }
076
077        private MessageInterpolator getFallback(String fallback) {
078                Class<?> interpolatorClass = ClassUtils.resolveClassName(fallback, null);
079                Object interpolator = BeanUtils.instantiateClass(interpolatorClass);
080                return (MessageInterpolator) interpolator;
081        }
082
083}