/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed 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
 *
 *      https://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.springframework.web.client;

import java.io.IOException;
import java.lang.reflect.Type;

import org.springframework.http.client.ClientHttpResponse;
import org.springframework.lang.Nullable;

/**
 * Generic callback interface used by {@link RestTemplate}'s retrieval methods
 * Implementations of this interface perform the actual work of extracting data
 * from a {@link ClientHttpResponse}, but don't need to worry about exception
 * handling or closing resources.
 *
 * <p>Used internally by the {@link RestTemplate}, but also useful for
 * application code. There is one available factory method, see
 * {@link RestTemplate#responseEntityExtractor(Type)}.
 *
 * @author Arjen Poutsma
 * @since 3.0
 * @param <T> the data type
 * @see RestTemplate#execute
 */
@FunctionalInterface
public interface ResponseExtractor<T> {

	/**
	 * Extract data from the given {@code ClientHttpResponse} and return it.
	 * @param response the HTTP response
	 * @return the extracted data
	 * @throws IOException in case of I/O errors
	 */
	@Nullable
	T extractData(ClientHttpResponse response) throws IOException;

}
