Add multipart support to ServerWebExchange

Issue: SPR-14546

spring-web/src/main/java/org/springframework/web/server/ServerWebExchange.java

@@ -24,6 +24,7 @@ import java.util.function.Consumer;
 
 import reactor.core.publisher.Mono;
 
+import org.springframework.http.codec.multipart.Part;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.util.MultiValueMap;
@@ -82,6 +83,12 @@ public interface ServerWebExchange {
 	 */
 	Mono<MultiValueMap<String, String>> getFormData();
 
+	/**
+	 * Return the form parts from the body of the request or an empty {@code Mono}
+	 * if the Content-Type is not "multipart/form-data".
+	 */
+	Mono<MultiValueMap<String, Part>> getMultipartData();
+
 	/**
 	 * Return a combined map that represents both
 	 * {@link ServerHttpRequest#getQueryParams()} and {@link #getFormData()}

spring-web/src/main/java/org/springframework/web/server/ServerWebExchangeDecorator.java

@@ -22,6 +22,7 @@ import java.util.Optional;
 
 import reactor.core.publisher.Mono;
 
+import org.springframework.http.codec.multipart.Part;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.util.Assert;
@@ -93,6 +94,11 @@ public class ServerWebExchangeDecorator implements ServerWebExchange {
 		return getDelegate().getFormData();
 	}
 
+	@Override
+	public Mono<MultiValueMap<String, Part>> getMultipartData() {
+		return getDelegate().getMultipartData();
+	}
+
 	@Override
 	public Mono<MultiValueMap<String, String>> getRequestParams() {
 		return getDelegate().getRequestParams();

spring-web/src/main/java/org/springframework/web/server/adapter/DefaultServerWebExchange.java

@@ -36,6 +36,7 @@ import org.springframework.http.InvalidMediaTypeException;
 import org.springframework.http.MediaType;
 import org.springframework.http.codec.HttpMessageReader;
 import org.springframework.http.codec.ServerCodecConfigurer;
+import org.springframework.http.codec.multipart.Part;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.util.Assert;
@@ -48,6 +49,7 @@ import org.springframework.web.server.WebSession;
 import org.springframework.web.server.session.WebSessionManager;
 
 import static org.springframework.http.MediaType.*;
+import static org.springframework.http.codec.multipart.MultipartHttpMessageReader.*;
 
 /**
  * Default implementation of {@link ServerWebExchange}.
@@ -66,6 +68,10 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 			Mono.just(CollectionUtils.unmodifiableMultiValueMap(new LinkedMultiValueMap<String, String>(0)))
 					.cache();
 
+	private static final Mono<MultiValueMap<String, Part>> EMPTY_MULTIPART_DATA =
+			Mono.just(CollectionUtils.unmodifiableMultiValueMap(new LinkedMultiValueMap<String, Part>(0)))
+					.cache();
+
 
 	private final ServerHttpRequest request;
 
@@ -77,6 +83,8 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 
 	private final Mono<MultiValueMap<String, String>> formDataMono;
 
+	private final Mono<MultiValueMap<String, Part>> multipartDataMono;
+
 	private final Mono<MultiValueMap<String, String>> requestParamsMono;
 
 	private volatile boolean notModified;
@@ -97,6 +105,7 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 		this.response = response;
 		this.sessionMono = sessionManager.getSession(this).cache();
 		this.formDataMono = initFormData(request, codecConfigurer);
+		this.multipartDataMono = initMultipartData(request, codecConfigurer);
 		this.requestParamsMono = initRequestParams(request, this.formDataMono);
 
 	}
@@ -126,6 +135,31 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 		return EMPTY_FORM_DATA;
 	}
 
+	@SuppressWarnings("unchecked")
+	private static Mono<MultiValueMap<String, Part>> initMultipartData(
+			ServerHttpRequest request, ServerCodecConfigurer codecConfigurer) {
+
+		MediaType contentType;
+		try {
+			contentType = request.getHeaders().getContentType();
+			if (MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+				return ((HttpMessageReader<MultiValueMap<String, Part>>)codecConfigurer
+						.getReaders()
+						.stream()
+						.filter(messageReader -> messageReader.canRead(MULTIPART_VALUE_TYPE, MULTIPART_FORM_DATA))
+						.findFirst()
+						.orElseThrow(() -> new IllegalStateException("Could not find HttpMessageReader that supports " + MULTIPART_FORM_DATA)))
+						.readMono(FORM_DATA_VALUE_TYPE, request, Collections.emptyMap())
+						.switchIfEmpty(EMPTY_MULTIPART_DATA)
+						.cache();
+			}
+		}
+		catch (InvalidMediaTypeException ex) {
+			// Ignore
+		}
+		return EMPTY_MULTIPART_DATA;
+	}
+
 	private static Mono<MultiValueMap<String, String>> initRequestParams(
 			ServerHttpRequest request, Mono<MultiValueMap<String, String>> formDataMono) {
 
@@ -184,6 +218,11 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 		return this.formDataMono;
 	}
 
+	@Override
+	public Mono<MultiValueMap<String, Part>> getMultipartData() {
+		return this.multipartDataMono;
+	}
+
 	@Override
 	public Mono<MultiValueMap<String, String>> getRequestParams() {
 		return this.requestParamsMono;

spring-web/src/test/java/org/springframework/http/server/reactive/MultipartIntegrationTests.java

@@ -0,0 +1,120 @@
+/*
+ * 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.http.server.reactive;
+
+import java.net.URI;
+import java.util.Optional;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+import reactor.core.publisher.Mono;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.RequestEntity;
+import org.springframework.http.ResponseEntity;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.RestTemplate;
+import org.springframework.http.codec.multipart.Part;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.WebHandler;
+import org.springframework.web.server.adapter.HttpWebHandlerAdapter;
+
+public class MultipartIntegrationTests extends AbstractHttpHandlerIntegrationTests {
+
+	@Override
+	protected HttpHandler createHttpHandler() {
+		HttpWebHandlerAdapter handler = new HttpWebHandlerAdapter(new CheckRequestHandler());
+		return handler;
+	}
+
+	@Test
+	public void getFormParts() throws Exception {
+		RestTemplate restTemplate = new RestTemplate();
+		RequestEntity<MultiValueMap<String, Object>> request = RequestEntity
+				.post(new URI("http://localhost:" + port + "/form-parts"))
+				.contentType(MediaType.MULTIPART_FORM_DATA)
+				.body(generateBody());
+		ResponseEntity<Void> response = restTemplate.exchange(request, Void.class);
+		assertEquals(HttpStatus.OK, response.getStatusCode());
+	}
+
+	private MultiValueMap<String, Object> generateBody() {
+		HttpHeaders fooHeaders = new HttpHeaders();
+		fooHeaders.setContentType(MediaType.TEXT_PLAIN);
+		ClassPathResource fooResource = new ClassPathResource("org/springframework/http/codec/multipart/foo.txt");
+		HttpEntity<ClassPathResource> fooPart = new HttpEntity<>(fooResource, fooHeaders);
+		HttpEntity<String> barPart = new HttpEntity<>("bar");
+		MultiValueMap<String, Object> parts = new LinkedMultiValueMap<>();
+		parts.add("fooPart", fooPart);
+		parts.add("barPart", barPart);
+		return parts;
+	}
+
+	public static class CheckRequestHandler implements WebHandler {
+
+		@Override
+		public Mono<Void> handle(ServerWebExchange exchange) {
+
+			if (exchange.getRequest().getURI().getPath().equals("/form-parts")) {
+				return assertGetFormParts(exchange);
+			}
+			return Mono.error(new AssertionError());
+		}
+
+		private Mono<Void> assertGetFormParts(ServerWebExchange exchange) {
+			return exchange
+					.getMultipartData()
+					.doOnNext(parts -> {
+						assertEquals(2, parts.size());
+						assertTrue(parts.containsKey("fooPart"));
+						assertFooPart(parts.getFirst("fooPart"));
+						assertTrue(parts.containsKey("barPart"));
+						assertBarPart(parts.getFirst("barPart"));
+					})
+					.then();
+		}
+
+		private void assertFooPart(Part part) {
+			assertEquals("fooPart", part.getName());
+			Optional<String> filename = part.getFilename();
+			assertTrue(filename.isPresent());
+			assertEquals("foo.txt", filename.get());
+			DataBuffer buffer = part
+					.getContent()
+					.reduce((s1, s2) -> s1.write(s2))
+					.block();
+			assertEquals(12, buffer.readableByteCount());
+			byte[] byteContent = new byte[12];
+			buffer.read(byteContent);
+			assertEquals("Lorem\nIpsum\n", new String(byteContent));
+		}
+
+		private void assertBarPart(Part part) {
+			assertEquals("barPart", part.getName());
+			Optional<String> filename = part.getFilename();
+			assertFalse(filename.isPresent());
+			assertEquals("bar", part.getContentAsString().block());
+		}
+	}
+
+}