/*
* Copyright 2002-2010 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
*
* http://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.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.util.Assert;
/**
* Response extractor that uses the given {@linkplain HttpMessageConverter entity converters} to convert the response
* into a type <code>T</code>.
*
* @author Arjen Poutsma
* @see RestTemplate
* @since 3.0
*/
public class HttpMessageConverterExtractor<T> implements ResponseExtractor<T> {
private final Class<T> responseType;
private final List<HttpMessageConverter<?>> messageConverters;
private final Log logger;
/**
* Creates a new instance of the {@code HttpMessageConverterExtractor} with the given response type and message
* converters. The given converters must support the response type.
*/
public HttpMessageConverterExtractor(Class<T> responseType, List<HttpMessageConverter<?>> messageConverters) {
this(responseType, messageConverters, LogFactory.getLog(HttpMessageConverterExtractor.class));
}
HttpMessageConverterExtractor(Class<T> responseType, List<HttpMessageConverter<?>> messageConverters, Log logger) {
Assert.notNull(responseType, "'responseType' must not be null");
Assert.notEmpty(messageConverters, "'messageConverters' must not be empty");
this.responseType = responseType;
this.messageConverters = messageConverters;
this.logger = logger;
}
@SuppressWarnings("unchecked")
public T extractData(ClientHttpResponse response) throws IOException {
MediaType contentType = response.getHeaders().getContentType();
if (contentType == null) {
throw new RestClientException("Cannot extract response: no Content-Type found");
}
for (HttpMessageConverter messageConverter : messageConverters) {
if (messageConverter.canRead(responseType, contentType)) {
if (logger.isDebugEnabled()) {
logger.debug("Reading [" + responseType.getName() + "] as \"" + contentType
+"\" using [" + messageConverter + "]");
}
return (T) messageConverter.read(this.responseType, response);
}
}
throw new RestClientException(
"Could not extract response: no suitable HttpMessageConverter found for response type [" +
this.responseType.getName() + "] and content type [" + contentType + "]");
}
}
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