org.springframework.web.client.HttpMessageConverterExtractor Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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.lang.reflect.Type;
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.GenericHttpMessageConverter;
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}.
*
* @author Arjen Poutsma
* @since 3.0
* @see RestTemplate
*/
public class HttpMessageConverterExtractor implements ResponseExtractor {
private final Type responseType;
private final Class responseClass;
private final List> messageConverters;
private final Log logger;
/**
* Create 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 responseType, List> messageConverters) {
this((Type) responseType, messageConverters);
}
/**
* 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(Type responseType, List> messageConverters) {
this(responseType, messageConverters, LogFactory.getLog(HttpMessageConverterExtractor.class));
}
@SuppressWarnings("unchecked")
HttpMessageConverterExtractor(Type responseType, List> messageConverters, Log logger) {
Assert.notNull(responseType, "'responseType' must not be null");
Assert.notEmpty(messageConverters, "'messageConverters' must not be empty");
this.responseType = responseType;
this.responseClass = (responseType instanceof Class) ? (Class) responseType : null;
this.messageConverters = messageConverters;
this.logger = logger;
}
@Override
@SuppressWarnings({"unchecked", "rawtypes", "resource"})
public T extractData(ClientHttpResponse response) throws IOException {
MessageBodyClientHttpResponseWrapper responseWrapper = new MessageBodyClientHttpResponseWrapper(response);
if (!responseWrapper.hasMessageBody() || responseWrapper.hasEmptyMessageBody()) {
return null;
}
MediaType contentType = getContentType(responseWrapper);
for (HttpMessageConverter messageConverter : this.messageConverters) {
if (messageConverter instanceof GenericHttpMessageConverter) {
GenericHttpMessageConverter genericMessageConverter =
(GenericHttpMessageConverter) messageConverter;
if (genericMessageConverter.canRead(this.responseType, null, contentType)) {
if (logger.isDebugEnabled()) {
logger.debug("Reading [" + this.responseType + "] as \"" +
contentType + "\" using [" + messageConverter + "]");
}
return (T) genericMessageConverter.read(this.responseType, null, responseWrapper);
}
}
if (this.responseClass != null) {
if (messageConverter.canRead(this.responseClass, contentType)) {
if (logger.isDebugEnabled()) {
logger.debug("Reading [" + this.responseClass.getName() + "] as \"" +
contentType + "\" using [" + messageConverter + "]");
}
return (T) messageConverter.read((Class) this.responseClass, responseWrapper);
}
}
}
throw new RestClientException("Could not extract response: no suitable HttpMessageConverter found " +
"for response type [" + this.responseType + "] and content type [" + contentType + "]");
}
private MediaType getContentType(ClientHttpResponse response) {
MediaType contentType = response.getHeaders().getContentType();
if (contentType == null) {
if (logger.isTraceEnabled()) {
logger.trace("No Content-Type header found, defaulting to application/octet-stream");
}
contentType = MediaType.APPLICATION_OCTET_STREAM;
}
return contentType;
}
}