001/*
002 * Copyright 2002-2018 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 *      https://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.web.client;
018
019import java.io.IOException;
020import java.lang.reflect.Type;
021
022import org.springframework.http.client.ClientHttpResponse;
023import org.springframework.lang.Nullable;
024
025/**
026 * Generic callback interface used by {@link RestTemplate}'s retrieval methods
027 * Implementations of this interface perform the actual work of extracting data
028 * from a {@link ClientHttpResponse}, but don't need to worry about exception
029 * handling or closing resources.
030 *
031 * <p>Used internally by the {@link RestTemplate}, but also useful for
032 * application code. There is one available factory method, see
033 * {@link RestTemplate#responseEntityExtractor(Type)}.
034 *
035 * @author Arjen Poutsma
036 * @since 3.0
037 * @param <T> the data type
038 * @see RestTemplate#execute
039 */
040@FunctionalInterface
041public interface ResponseExtractor<T> {
042
043        /**
044         * Extract data from the given {@code ClientHttpResponse} and return it.
045         * @param response the HTTP response
046         * @return the extracted data
047         * @throws IOException in case of I/O errors
048         */
049        @Nullable
050        T extractData(ClientHttpResponse response) throws IOException;
051
052}