Refactor Contents to DefaultParts

This commit moves the Contents abstraction into DefaultParts

See gh-27613

spring-web/src/main/java/org/springframework/http/codec/multipart/DefaultParts.java

@@ -16,10 +16,15 @@
 
 package org.springframework.http.codec.multipart;
 
+import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.StandardOpenOption;
+import java.util.concurrent.Callable;
 
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.core.scheduler.Scheduler;
 
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.DataBufferUtils;
@@ -50,17 +55,40 @@ public static FormFieldPart formFieldPart(HttpHeaders headers, String value) {
 	}
 
 	/**
-	 * Create a new {@link Part} or {@link FilePart} with the given parameters.
+	 * Create a new {@link Part} or {@link FilePart} based on a flux of data
+	 * buffers. Returns {@link FilePart} if the {@code Content-Disposition} of
+	 * the given headers contains a filename, or a "normal" {@link Part}
+	 * otherwise.
+	 * @param headers the part headers
+	 * @param dataBuffers the content of the part
+	 * @return {@link Part} or {@link FilePart}, depending on {@link HttpHeaders#getContentDisposition()}
+	 */
+	public static Part part(HttpHeaders headers, Flux<DataBuffer> dataBuffers) {
+		Assert.notNull(headers, "Headers must not be null");
+		Assert.notNull(dataBuffers, "DataBuffers must not be null");
+
+		return partInternal(headers, new FluxContent(dataBuffers));
+	}
+
+	/**
+	 * Create a new {@link Part} or {@link FilePart} based on the given file.
 	 * Returns {@link FilePart} if the {@code Content-Disposition} of the given
 	 * headers contains a filename, or a "normal" {@link Part} otherwise
 	 * @param headers the part headers
-	 * @param content the content of the part
+	 * @param file  the file
+	 * @param scheduler the scheduler used for reading the file
 	 * @return {@link Part} or {@link FilePart}, depending on {@link HttpHeaders#getContentDisposition()}
 	 */
-	public static Part part(HttpHeaders headers, Content content) {
+	public static Part part(HttpHeaders headers, Path file, Scheduler scheduler) {
 		Assert.notNull(headers, "Headers must not be null");
-		Assert.notNull(content, "Content must not be null");
+		Assert.notNull(file, "File must not be null");
+		Assert.notNull(scheduler, "Scheduler must not be null");
+
+		return partInternal(headers, new FileContent(file, scheduler));
+	}
+
 
+	private static Part partInternal(HttpHeaders headers, Content content) {
 		String filename = headers.getContentDisposition().getFilename();
 		if (filename != null) {
 			return new DefaultFilePart(headers, content);
@@ -142,7 +170,8 @@ public String toString() {
 	 */
 	private static class DefaultPart extends AbstractPart {
 
-		private final Content content;
+		protected final Content content;
+
 
 		public DefaultPart(HttpHeaders headers, Content content) {
 			super(headers);
@@ -191,7 +220,7 @@ public String filename() {
 
 		@Override
 		public Mono<Void> transferTo(Path dest) {
-			return DataBufferUtils.write(content(), dest);
+			return this.content.transferTo(dest);
 		}
 
 		@Override
@@ -200,7 +229,7 @@ public String toString() {
 			String name = contentDisposition.getName();
 			String filename = contentDisposition.getFilename();
 			if (name != null) {
-				return "DefaultFilePart{" + name() + " (" + filename + ")}";
+				return "DefaultFilePart{" + name + " (" + filename + ")}";
 			}
 			else {
 				return "DefaultFilePart{(" + filename + ")}";
@@ -209,4 +238,100 @@ public String toString() {
 
 	}
 
+
+	/**
+	 * Part content abstraction.
+	 */
+	private interface Content {
+
+		Flux<DataBuffer> content();
+
+		Mono<Void> transferTo(Path dest);
+
+		Mono<Void> delete();
+
+	}
+
+	/**
+	 * {@code Content} implementation based on a flux of data buffers.
+	 */
+	private static final class FluxContent implements Content {
+
+		private final Flux<DataBuffer> content;
+
+
+		public FluxContent(Flux<DataBuffer> content) {
+			this.content = content;
+		}
+
+
+		@Override
+		public Flux<DataBuffer> content() {
+			return this.content;
+		}
+
+		@Override
+		public Mono<Void> transferTo(Path dest) {
+			return DataBufferUtils.write(this.content, dest);
+		}
+
+		@Override
+		public Mono<Void> delete() {
+			return Mono.empty();
+		}
+
+	}
+
+
+	/**
+	 * {@code Content} implementation based on a file.
+	 */
+	private static final class FileContent implements Content {
+
+		private final Path file;
+
+		private final Scheduler scheduler;
+
+
+		public FileContent(Path file, Scheduler scheduler) {
+			this.file = file;
+			this.scheduler = scheduler;
+		}
+
+
+		@Override
+		public Flux<DataBuffer> content() {
+			return DataBufferUtils.readByteChannel(
+					() -> Files.newByteChannel(this.file, StandardOpenOption.READ),
+							DefaultDataBufferFactory.sharedInstance, 1024)
+					.subscribeOn(this.scheduler);
+		}
+
+		@Override
+		public Mono<Void> transferTo(Path dest) {
+			return blockingOperation(() -> Files.copy(this.file, dest, StandardCopyOption.REPLACE_EXISTING));
+		}
+
+		@Override
+		public Mono<Void> delete() {
+			return blockingOperation(() -> {
+				Files.delete(this.file);
+				return null;
+			});
+		}
+
+		private Mono<Void> blockingOperation(Callable<?> callable) {
+			return Mono.<Void>create(sink -> {
+						try {
+							callable.call();
+							sink.success();
+						}
+						catch (Exception ex) {
+							sink.error(ex);
+						}
+					})
+					.subscribeOn(this.scheduler);
+		}
+	}
+
 }

spring-web/src/main/java/org/springframework/http/codec/multipart/PartGenerator.java

@@ -160,7 +160,7 @@ else if (!this.streaming) {
 					requestToken();
 				}
 			});
-			emitPart(DefaultParts.part(headers, Content.fromFlux(streamingContent)));
+			emitPart(DefaultParts.part(headers, streamingContent));
 		}
 	}
 
@@ -518,7 +518,7 @@ private void emitMemoryPart() {
 			}
 			this.content.clear();
 			Flux<DataBuffer> content = Flux.just(DefaultDataBufferFactory.sharedInstance.wrap(bytes));
-			emitPart(DefaultParts.part(this.headers, Content.fromFlux(content)));
+			emitPart(DefaultParts.part(this.headers, content));
 		}
 
 		@Override
@@ -674,8 +674,7 @@ public void body(DataBuffer dataBuffer) {
 		@Override
 		public void partComplete(boolean finalPart) {
 			MultipartUtils.closeChannel(this.channel);
-			emitPart(DefaultParts.part(this.headers,
-					Content.fromFile(this.file, PartGenerator.this.blockingOperationScheduler)));
+			emitPart(DefaultParts.part(this.headers, this.file, PartGenerator.this.blockingOperationScheduler));
 			if (finalPart) {
 				emitComplete();
 			}