/*
* Copyright 2002-2014 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.springframework.http.HttpStatus;
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;
import android.util.Log;
/**
* Response extractor that uses the given {@linkplain HttpMessageConverter entity
* converters} to convert the response into a type {@code T}.
*
* @author Arjen Poutsma
* @author Roy Clarkson
* @see RestTemplate
* @since 1.0
*/
public class HttpMessageConverterExtractor<T> implements ResponseExtractor<T> {
private static final String TAG = "RestTemplate";
private final Type responseType;
private final Class<T> responseClass;
private final List<HttpMessageConverter<?>> 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(Class<T> responseType, List<HttpMessageConverter<?>> 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.
*/
@SuppressWarnings("unchecked")
public HttpMessageConverterExtractor(Type responseType, List<HttpMessageConverter<?>> messageConverters) {
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<T>) responseType : null;
this.messageConverters = messageConverters;
}
@SuppressWarnings("unchecked")
public T extractData(ClientHttpResponse response) throws IOException {
if (!hasMessageBody(response)) {
return null;
}
MediaType contentType = getContentType(response);
for (HttpMessageConverter messageConverter : this.messageConverters) {
if (messageConverter instanceof GenericHttpMessageConverter) {
GenericHttpMessageConverter genericMessageConverter = (GenericHttpMessageConverter) messageConverter;
if (genericMessageConverter.canRead(this.responseType, null, contentType)) {
if (Log.isLoggable(TAG, Log.DEBUG)) {
Log.d(TAG, "Reading [" + this.responseType + "] as \"" +
contentType + "\" using [" + messageConverter + "]");
}
return (T) genericMessageConverter.read(this.responseType, null, response);
}
}
if (this.responseClass != null) {
if (messageConverter.canRead(this.responseClass, contentType)) {
if (Log.isLoggable(TAG, Log.DEBUG)) {
Log.d(TAG, "Reading [" + this.responseClass.getName() + "] as \"" +
contentType + "\" using [" + messageConverter + "]");
}
return (T) messageConverter.read(this.responseClass, response);
}
}
}
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 (Log.isLoggable(TAG, Log.VERBOSE)) {
Log.v(TAG, "No Content-Type header found, defaulting to application/octet-stream");
}
contentType = MediaType.APPLICATION_OCTET_STREAM;
}
return contentType;
}
/**
* Indicates whether the given response has a message body. <p>Default implementation
* returns {@code false} for a response status of {@code 204} or {@code 304}, or a {@code
* Content-Length} of {@code 0}.
*
* @param response the response to check for a message body
* @return {@code true} if the response has a body, {@code false} otherwise
* @throws IOException in case of I/O errors
*/
protected boolean hasMessageBody(ClientHttpResponse response) throws IOException {
HttpStatus responseStatus = response.getStatusCode();
if (responseStatus == HttpStatus.NO_CONTENT ||
responseStatus == HttpStatus.NOT_MODIFIED) {
return false;
}
long contentLength = response.getHeaders().getContentLength();
return contentLength != 0;
}
}