Simplify use of InputStream with RestClient

Closes gh-36380

spring-web/src/main/java/org/springframework/web/client/DefaultRestClient.java

@@ -42,6 +42,7 @@ import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.ResolvableType;
+import org.springframework.core.io.InputStreamResource;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpRequest;
@@ -253,6 +254,10 @@ final class DefaultRestClient implements RestClient {
 				}
 			}
 
+			if (bodyClass.equals(InputStream.class)) {
+				return (T) responseWrapper.getBody();
+			}
+
 			throw new UnknownContentTypeException(bodyType, contentType,
 					responseWrapper.getStatusCode(), responseWrapper.getStatusText(),
 					responseWrapper.getHeaders(), RestClientUtils.getBody(responseWrapper));
@@ -609,7 +614,11 @@ final class DefaultRestClient implements RestClient {
 				clientResponse = clientRequest.execute();
 				observationContext.setResponse(clientResponse);
 				ConvertibleClientHttpResponse convertibleWrapper = new DefaultConvertibleClientHttpResponse(clientResponse, this.hints);
-				return exchangeFunction.exchange(clientRequest, convertibleWrapper);
+				T result = exchangeFunction.exchange(clientRequest, convertibleWrapper);
+				if (close && isStreamingResult(result)) {
+					close = false;
+				}
+				return result;
 			}
 			catch (IOException ex) {
 				ResourceAccessException resourceAccessException = createResourceAccessException(uri, this.httpMethod, ex);
@@ -746,6 +755,10 @@ final class DefaultRestClient implements RestClient {
 			return request;
 		}
 
+		private static boolean isStreamingResult(@Nullable Object result) {
+			return (result instanceof InputStream || result instanceof InputStreamResource);
+		}
+
 		private static ResourceAccessException createResourceAccessException(URI url, HttpMethod method, IOException ex) {
 			StringBuilder msg = new StringBuilder("I/O error on ");
 			msg.append(method.name());

spring-web/src/main/java/org/springframework/web/client/support/RestClientAdapter.java

@@ -16,8 +16,6 @@
 
 package org.springframework.web.client.support;
 
-import java.io.IOException;
-import java.io.InputStream;
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.List;
@@ -75,8 +73,7 @@ public final class RestClientAdapter implements HttpExchangeAdapter {
 
 	@Override
 	public <T> @Nullable T exchangeForBody(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
-		return (bodyType.getType().equals(InputStream.class) ?
-				exchangeForInputStream(values) : newRequest(values).retrieve().body(bodyType));
+		return newRequest(values).retrieve().body(bodyType);
 	}
 
 	@Override
@@ -86,21 +83,7 @@ public final class RestClientAdapter implements HttpExchangeAdapter {
 
 	@Override
 	public <T> ResponseEntity<T> exchangeForEntity(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
-		return (bodyType.getType().equals(InputStream.class) ?
-				exchangeForEntityInputStream(values) : newRequest(values).retrieve().toEntity(bodyType));
-	}
-
-	@SuppressWarnings("unchecked")
-	private <T> T exchangeForInputStream(HttpRequestValues values) {
-		return (T) newRequest(values).exchange((request, response) -> getInputStream(response), false);
-	}
-
-	@SuppressWarnings("unchecked")
-	private <T> ResponseEntity<T> exchangeForEntityInputStream(HttpRequestValues values) {
-		return (ResponseEntity<T>) newRequest(values).exchangeForRequiredValue((request, response) ->
-				ResponseEntity.status(response.getStatusCode())
-						.headers(response.getHeaders())
-						.body(getInputStream(response)), false);
+		return newRequest(values).retrieve().toEntity(bodyType);
 	}
 
 	@SuppressWarnings("unchecked")
@@ -162,16 +145,6 @@ public final class RestClientAdapter implements HttpExchangeAdapter {
 		return bodySpec;
 	}
 
-	private static InputStream getInputStream(
-			RestClient.RequestHeadersSpec.ConvertibleClientHttpResponse response) throws IOException {
-
-		if (response.getStatusCode().isError()) {
-			throw response.createException();
-		}
-		return response.getBody();
-	}
-
-
 
 	/**
 	 * Create a {@link RestClientAdapter} for the given {@link RestClient}.

spring-web/src/test/java/org/springframework/web/client/DefaultRestClientTests.java

@@ -18,6 +18,7 @@ package org.springframework.web.client;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.URI;
 
 import org.junit.jupiter.api.BeforeEach;
@@ -36,6 +37,8 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link DefaultRestClient}.
@@ -117,6 +120,21 @@ class DefaultRestClientTests {
 		);
 	}
 
+	@Test
+	void inputStreamBody() throws IOException {
+		mockSentRequest(HttpMethod.GET, "https://example.org");
+		mockResponseStatus(HttpStatus.OK);
+		mockResponseBody("Hello World", MediaType.TEXT_PLAIN);
+
+		InputStream result = this.client.get()
+				.uri("https://example.org")
+				.retrieve()
+				.requiredBody(InputStream.class);
+
+		assertThat(result).isInstanceOf(InputStream.class);
+		verify(this.response, times(0)).close();
+	}
+
 
 	private void mockSentRequest(HttpMethod method, String uri) throws IOException {
 		given(this.requestFactory.createRequest(URI.create(uri), method)).willReturn(this.request);