001/*
002 * Copyright 2012-2018 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.web.client;
018
019import java.util.Collections;
020import java.util.LinkedHashMap;
021import java.util.Map;
022import java.util.function.Supplier;
023
024import org.springframework.beans.BeanUtils;
025import org.springframework.http.client.ClientHttpRequestFactory;
026import org.springframework.http.client.SimpleClientHttpRequestFactory;
027import org.springframework.util.ClassUtils;
028
029/**
030 * A supplier for {@link ClientHttpRequestFactory} that detects the preferred candidate
031 * based on the available implementations on the classpath.
032 *
033 * @author Stephane Nicoll
034 * @since 2.1.0
035 */
036public class ClientHttpRequestFactorySupplier
037                implements Supplier<ClientHttpRequestFactory> {
038
039        private static final Map<String, String> REQUEST_FACTORY_CANDIDATES;
040
041        static {
042                Map<String, String> candidates = new LinkedHashMap<>();
043                candidates.put("org.apache.http.client.HttpClient",
044                                "org.springframework.http.client.HttpComponentsClientHttpRequestFactory");
045                candidates.put("okhttp3.OkHttpClient",
046                                "org.springframework.http.client.OkHttp3ClientHttpRequestFactory");
047                REQUEST_FACTORY_CANDIDATES = Collections.unmodifiableMap(candidates);
048        }
049
050        @Override
051        public ClientHttpRequestFactory get() {
052                for (Map.Entry<String, String> candidate : REQUEST_FACTORY_CANDIDATES
053                                .entrySet()) {
054                        ClassLoader classLoader = getClass().getClassLoader();
055                        if (ClassUtils.isPresent(candidate.getKey(), classLoader)) {
056                                Class<?> factoryClass = ClassUtils.resolveClassName(candidate.getValue(),
057                                                classLoader);
058                                return (ClientHttpRequestFactory) BeanUtils
059                                                .instantiateClass(factoryClass);
060                        }
061                }
062                return new SimpleClientHttpRequestFactory();
063        }
064
065}