SPR-5808 - Make HttpMessageConverterExtractor top level class

org.springframework.web/src/main/java/org/springframework/web/client/HttpMessageConverterExtractor.java

+/*
+ * Copyright 2002-2009 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.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<T>> 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<T>> messageConverters) {
+		Assert.notNull(responseType, "'responseType' must not be null");
+		Assert.notEmpty(messageConverters, "'messageConverters' must not be empty");
+		this.responseType = responseType;
+		this.messageConverters = messageConverters;
+	}
+
+	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<T> messageConverter : messageConverters) {
+			for (MediaType supportedMediaType : messageConverter.getSupportedMediaTypes()) {
+				if (supportedMediaType.includes(contentType)) {
+					return 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 + "]");
+	}
+
+}

org.springframework.web/src/main/java/org/springframework/web/client/RestTemplate.java

@@ -166,16 +166,18 @@ public class RestTemplate extends HttpAccessor implements RestOperations {
 	public <T> T getForObject(String url, Class<T> responseType, String... urlVariables) throws RestClientException {
 
 		checkForSupportedMessageConverter(responseType);
+		List<HttpMessageConverter<T>> supportedMessageConverters = getSupportedMessageConverters(responseType);
 		return execute(url, HttpMethod.GET, new GetCallback<T>(responseType),
-				new HttpMessageConverterExtractor<T>(responseType), urlVariables);
+				new HttpMessageConverterExtractor<T>(responseType, supportedMessageConverters), urlVariables);
 	}
 
 	public <T> T getForObject(String url, Class<T> responseType, Map<String, String> urlVariables)
 			throws RestClientException {
 
 		checkForSupportedMessageConverter(responseType);
+		List<HttpMessageConverter<T>> supportedMessageConverters = getSupportedMessageConverters(responseType);
 		return execute(url, HttpMethod.GET, new GetCallback<T>(responseType),
-				new HttpMessageConverterExtractor<T>(responseType), urlVariables);
+				new HttpMessageConverterExtractor<T>(responseType, supportedMessageConverters), urlVariables);
 	}
 
 	// HEAD
@@ -381,37 +383,6 @@ public class RestTemplate extends HttpAccessor implements RestOperations {
 		}
 	}
 
-	/**
-	 * Response extractor that uses the registered {@linkplain HttpMessageConverter entity converters}
-	 * to convert the response into a type <code>T</code>.
-	 */
-	private class HttpMessageConverterExtractor<T> implements ResponseExtractor<T> {
-
-		private final Class<T> responseType;
-
-		private HttpMessageConverterExtractor(Class<T> responseType) {
-			this.responseType = responseType;
-		}
-
-		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<T> messageConverter : getSupportedMessageConverters(this.responseType)) {
-				for (MediaType supportedMediaType : messageConverter.getSupportedMediaTypes()) {
-					if (supportedMediaType.includes(contentType)) {
-						return 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 + "]");
-		}
-
-	}
-
 	/** Response extractor that extracts the response {@link HttpHeaders}. */
 	private static class HeadersExtractor implements ResponseExtractor<HttpHeaders> {