Expose getFilePath() on Resource interface for consistent NIO support

Closes gh-35435

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/propertyeditors/PathEditor.java

@@ -108,7 +108,7 @@ else if (nioPathCandidate && (!resource.isFile() || !resource.exists())) {
 		}
 		else {
 			try {
-				setValue(resource.getFile().toPath());
+				setValue(resource.getFilePath());
 			}
 			catch (IOException ex) {
 				String msg = "Could not resolve \"" + text + "\" to 'java.nio.file.Path' for " + resource + ": " +

spring-core/src/main/java/org/springframework/core/io/FileSystemResource.java

@@ -292,6 +292,14 @@ public File getFile() {
 		return (this.file != null ? this.file : this.filePath.toFile());
 	}
 
+	/**
+	 * This implementation returns the underlying NIO Path reference.
+	 */
+	@Override
+	public Path getFilePath() {
+		return this.filePath;
+	}
+
 	/**
 	 * This implementation opens a FileChannel for the underlying file.
 	 * @see java.nio.channels.FileChannel

spring-core/src/main/java/org/springframework/core/io/PathResource.java

@@ -219,15 +219,16 @@ public boolean isFile() {
 	 * This implementation returns the underlying {@link File} reference.
 	 */
 	@Override
-	public File getFile() throws IOException {
-		try {
-			return this.path.toFile();
-		}
-		catch (UnsupportedOperationException ex) {
-			// Only paths on the default file system can be converted to a File:
-			// Do exception translation for cases where conversion is not possible.
-			throw new FileNotFoundException(this.path + " cannot be resolved to absolute file path");
-		}
+	public File getFile() {
+		return this.path.toFile();
+	}
+
+	/**
+	 * This implementation returns the underlying {@link Path} reference.
+	 */
+	@Override
+	public Path getFilePath() {
+		return this.path;
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/io/Resource.java

@@ -25,6 +25,7 @@
 import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.charset.Charset;
+import java.nio.file.Path;
 
 import org.jspecify.annotations.Nullable;
 
@@ -91,11 +92,13 @@ default boolean isOpen() {
 
 	/**
 	 * Determine whether this resource represents a file in a file system.
-	 * <p>A value of {@code true} strongly suggests (but does not guarantee)
-	 * that a {@link #getFile()} call will succeed.
+	 * <p>A value of {@code true} suggests (but does not guarantee) that a
+	 * {@link #getFile()} call will succeed. For non-default file systems,
+	 * {@link #getFilePath()} is the more reliable follow-up call.
 	 * <p>This is conservatively {@code false} by default.
 	 * @since 5.0
 	 * @see #getFile()
+	 * @see #getFilePath()
 	 */
 	default boolean isFile() {
 		return false;
@@ -118,13 +121,26 @@ default boolean isFile() {
 
 	/**
 	 * Return a File handle for this resource.
-	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as
-	 * absolute file path, i.e. if the resource is not available in a file system
+	 * <p>Note: This only works for files in the default file system.
+	 * @throws UnsupportedOperationException if the resource is a file but cannot be
+	 * exposed as a {@code java.io.File}; try {@link #getFilePath()} instead
+	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as a file
 	 * @throws IOException in case of general resolution/reading failures
 	 * @see #getInputStream()
 	 */
 	File getFile() throws IOException;
 
+	/**
+	 * Return an NIO Path handle for this resource.
+	 * <p>Note: This works for files in non-default file systems as well.
+	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as a file
+	 * @throws IOException in case of general resolution/reading failures
+	 * @since 7.0
+	 */
+	default Path getFilePath() throws IOException {
+		return getFile().toPath();
+	}
+
 	/**
 	 * Return a {@link ReadableByteChannel}.
 	 * <p>It is expected that each call creates a <i>fresh</i> channel.

spring-core/src/main/java/org/springframework/core/io/buffer/DataBufferUtils.java

@@ -16,7 +16,6 @@
 
 package org.springframework.core.io.buffer;
 
-import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -223,17 +222,17 @@ public static Flux<DataBuffer> read(
 
 		try {
 			if (resource.isFile()) {
-				File file = resource.getFile();
+				Path filePath = resource.getFilePath();
 				return readAsynchronousFileChannel(
-						() -> AsynchronousFileChannel.open(file.toPath(), StandardOpenOption.READ),
+						() -> AsynchronousFileChannel.open(filePath, StandardOpenOption.READ),
 						position, bufferFactory, bufferSize);
 			}
 		}
 		catch (IOException ignore) {
 			// fallback to resource.readableChannel(), below
 		}
 		Flux<DataBuffer> result = readByteChannel(resource::readableChannel, bufferFactory, bufferSize);
-		return position == 0 ? result : skipUntilByteCount(result, position);
+		return (position == 0 ? result : skipUntilByteCount(result, position));
 	}
 
 

spring-core/src/test/java/org/springframework/core/io/PathResourceTests.java

@@ -186,10 +186,11 @@ void getUri() throws IOException {
 	}
 
 	@Test
-	void getFile() throws IOException {
+	void getFile() {
 		PathResource resource = new PathResource(TEST_FILE);
 		File file = new File(TEST_FILE);
 		assertThat(resource.getFile().getAbsoluteFile()).isEqualTo(file.getAbsoluteFile());
+		assertThat(resource.getFilePath()).isEqualTo(file.toPath());
 	}
 
 	@Test
@@ -198,7 +199,7 @@ void getFileUnsupported() {
 		given(path.normalize()).willReturn(path);
 		given(path.toFile()).willThrow(new UnsupportedOperationException());
 		PathResource resource = new PathResource(path);
-		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(resource::getFile);
+		assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(resource::getFile);
 	}
 
 	@Test
@@ -236,13 +237,13 @@ void createRelativeFromFile() {
 
 	@Test
 	void filename() {
-		Resource resource = new PathResource(TEST_FILE);
+		PathResource resource = new PathResource(TEST_FILE);
 		assertThat(resource.getFilename()).isEqualTo("example.properties");
 	}
 
 	@Test
 	void description() {
-		Resource resource = new PathResource(TEST_FILE);
+		PathResource resource = new PathResource(TEST_FILE);
 		assertThat(resource.getDescription()).contains("path [");
 		assertThat(resource.getDescription()).contains(TEST_FILE);
 	}
@@ -261,9 +262,9 @@ void directoryIsNotWritable() {
 
 	@Test
 	void equalsAndHashCode() {
-		Resource resource1 = new PathResource(TEST_FILE);
-		Resource resource2 = new PathResource(TEST_FILE);
-		Resource resource3 = new PathResource(TEST_DIR);
+		PathResource resource1 = new PathResource(TEST_FILE);
+		PathResource resource2 = new PathResource(TEST_FILE);
+		PathResource resource3 = new PathResource(TEST_DIR);
 		assertThat(resource1).isEqualTo(resource1);
 		assertThat(resource1).isEqualTo(resource2);
 		assertThat(resource2).isEqualTo(resource1);

spring-core/src/test/java/org/springframework/core/io/ResourceTests.java

@@ -55,6 +55,8 @@
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 import static org.junit.jupiter.params.provider.Arguments.argumentSet;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for various {@link Resource} implementations.
@@ -268,6 +270,16 @@ void relativeResourcesAreEqual() throws Exception {
 			assertThat(relative).isEqualTo(new FileSystemResource("dir/subdir"));
 		}
 
+		@Test
+		void getFilePath() throws Exception {
+			Path path = mock();
+			given(path.normalize()).willReturn(path);
+			given(path.toFile()).willThrow(new UnsupportedOperationException());
+			Resource resource = new FileSystemResource(path);
+			assertThat(resource.getFilePath()).isSameAs(path);
+			assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(resource::getFile);
+		}
+
 		@Test
 		void readableChannelProvidesContent() throws Exception {
 			Resource resource = new FileSystemResource(getClass().getResource("ResourceTests.class").getFile());

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

@@ -16,8 +16,9 @@
 
 package org.springframework.http.codec;
 
-import java.io.File;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.List;
 import java.util.Map;
 
@@ -193,17 +194,17 @@ private static Mono<Long> lengthOf(Resource resource) {
 
 		if (message instanceof ZeroCopyHttpOutputMessage zeroCopyHttpOutputMessage && resource.isFile()) {
 			try {
-				File file = resource.getFile();
-				long pos = region != null ? region.getPosition() : 0;
-				long count = region != null ? region.getCount() : file.length();
+				Path filePath = resource.getFilePath();
+				long pos = (region != null ? region.getPosition() : 0);
+				long count = (region != null ? region.getCount() : Files.size(filePath));
 				if (logger.isDebugEnabled()) {
 					String formatted = region != null ? "region " + pos + "-" + (count) + " of " : "";
 					logger.debug(Hints.getLogPrefix(hints) + "Zero-copy " + formatted + "[" + resource + "]");
 				}
-				return zeroCopyHttpOutputMessage.writeWith(file, pos, count);
+				return zeroCopyHttpOutputMessage.writeWith(filePath, pos, count);
 			}
-			catch (IOException ex) {
-				// should not happen
+			catch (IOException ignore) {
+				// returning null below leads to fallback code path
 			}
 		}
 		return null;

spring-webflux/src/main/java/org/springframework/web/reactive/resource/EncodedResourceResolver.java

@@ -23,6 +23,7 @@
 import java.net.URL;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.charset.Charset;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -240,6 +241,11 @@ public File getFile() throws IOException {
 			return this.encoded.getFile();
 		}
 
+		@Override
+		public Path getFilePath() throws IOException {
+			return this.encoded.getFilePath();
+		}
+
 		@Override
 		public InputStream getInputStream() throws IOException {
 			return this.encoded.getInputStream();

spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java

@@ -23,6 +23,7 @@
 import java.net.URL;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.charset.Charset;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
@@ -283,6 +284,11 @@ public File getFile() throws IOException {
 			return this.original.getFile();
 		}
 
+		@Override
+		public Path getFilePath() throws IOException {
+			return this.original.getFilePath();
+		}
+
 		@Override
 		public InputStream getInputStream() throws IOException {
 			return this.original.getInputStream();