Add DataBuffer BodyInserter/BodyExtractor

Added a BodyExtractor for Flux<DataBuffer>, and a BodyInserter for
Publisher<DataBuffer>

Issue: SPR-14918

spring-web/src/test/java/org/springframework/http/codec/BodyExtractorsTests.java

@@ -19,7 +19,6 @@ package org.springframework.http.codec;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
@@ -40,7 +39,6 @@ import org.springframework.http.ReactiveHttpInputMessage;
 import org.springframework.http.codec.json.Jackson2JsonDecoder;
 import org.springframework.http.codec.xml.Jaxb2XmlDecoder;
 import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
-import org.springframework.web.server.UnsupportedMediaTypeStatusException;
 
 /**
  * @author Arjen Poutsma
@@ -122,7 +120,7 @@ public class BodyExtractorsTests {
 		BodyExtractor.Context emptyContext = new BodyExtractor.Context() {
 			@Override
 			public Supplier<Stream<HttpMessageReader<?>>> messageReaders() {
-				return () -> Collections.<HttpMessageReader<?>>emptySet().stream();
+				return Stream::empty;
 			}
 		};
 
@@ -132,4 +130,24 @@ public class BodyExtractorsTests {
 				.verify();
 	}
 
+	@Test
+	public void toDataBuffers() throws Exception {
+		BodyExtractor<Flux<DataBuffer>, ReactiveHttpInputMessage> extractor = BodyExtractors.toDataBuffers();
+
+		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
+		DefaultDataBuffer dataBuffer =
+				factory.wrap(ByteBuffer.wrap("foo".getBytes(StandardCharsets.UTF_8)));
+		Flux<DataBuffer> body = Flux.just(dataBuffer);
+
+		MockServerHttpRequest request = new MockServerHttpRequest();
+		request.setBody(body);
+
+		Flux<DataBuffer> result = extractor.extract(request, this.context);
+
+		StepVerifier.create(result)
+				.expectNext(dataBuffer)
+				.expectComplete()
+				.verify();
+	}
+
 }

spring-web/src/test/java/org/springframework/http/codec/BodyInsertersTests.java

@@ -17,6 +17,7 @@
 package org.springframework.http.codec;
 
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -35,6 +36,7 @@ import org.springframework.core.codec.CharSequenceEncoder;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.core.io.buffer.DefaultDataBuffer;
 import org.springframework.core.io.buffer.DefaultDataBufferFactory;
 import org.springframework.http.ReactiveHttpOutputMessage;
 import org.springframework.http.codec.json.Jackson2JsonEncoder;
@@ -164,4 +166,26 @@ public class BodyInsertersTests {
 		StepVerifier.create(result).expectNextCount(0).expectComplete().verify();
 	}
 
+	@Test
+	public void ofDataBuffers() throws Exception {
+		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
+		DefaultDataBuffer dataBuffer =
+				factory.wrap(ByteBuffer.wrap("foo".getBytes(StandardCharsets.UTF_8)));
+		Flux<DataBuffer> body = Flux.just(dataBuffer);
+
+		BodyInserter<Flux<DataBuffer>, ReactiveHttpOutputMessage> inserter = BodyInserters.fromDataBuffers(body);
+
+		assertEquals(body, inserter.t());
+
+		MockServerHttpResponse response = new MockServerHttpResponse();
+		Mono<Void> result = inserter.insert(response, this.context);
+		StepVerifier.create(result).expectComplete().verify();
+
+		StepVerifier.create(response.getBody())
+				.expectNext(dataBuffer)
+				.expectComplete()
+				.verify();
+	}
+
+
 }