Provide graceful fallback for non-default NIO file systems

Closes spring-projectsgh-35443

Author: jhoeller

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

@@ -117,8 +117,10 @@ 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}; an alternative to {@code FileNotFoundException}
+	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as a file
 	 * @throws IOException in case of general resolution/reading failures
 	 * @see #getInputStream()
 	 */

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.getFile().toPath();
 				return readAsynchronousFileChannel(
-						() -> AsynchronousFileChannel.open(file.toPath(), StandardOpenOption.READ),
+						() -> AsynchronousFileChannel.open(filePath, StandardOpenOption.READ),
 						position, bufferFactory, bufferSize);
 			}
 		}
-		catch (IOException ignore) {
+		catch (IOException | UnsupportedOperationException 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/main/java/org/springframework/util/FileSystemUtils.java

@@ -86,13 +86,12 @@ public static boolean deleteRecursively(@Nullable Path root) throws IOException
 
 		Files.walkFileTree(root, new SimpleFileVisitor<>() {
 			@Override
-			public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+			public FileVisitResult visitFile(Path file, BasicFileAttributes attr) throws IOException {
 				Files.delete(file);
 				return FileVisitResult.CONTINUE;
 			}
-
 			@Override
-			public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+			public FileVisitResult postVisitDirectory(Path dir, IOException ex) throws IOException {
 				Files.delete(dir);
 				return FileVisitResult.CONTINUE;
 			}
@@ -127,19 +126,34 @@ public static void copyRecursively(Path src, Path dest) throws IOException {
 		BasicFileAttributes srcAttr = Files.readAttributes(src, BasicFileAttributes.class);
 
 		if (srcAttr.isDirectory()) {
-			Files.walkFileTree(src, EnumSet.of(FOLLOW_LINKS), Integer.MAX_VALUE, new SimpleFileVisitor<>() {
-				@Override
-				public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
-					Files.createDirectories(dest.resolve(src.relativize(dir)));
-					return FileVisitResult.CONTINUE;
-				}
-
-				@Override
-				public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
-					Files.copy(file, dest.resolve(src.relativize(file)), StandardCopyOption.REPLACE_EXISTING);
-					return FileVisitResult.CONTINUE;
-				}
-			});
+			if (src.getClass() == dest.getClass()) {  // dest.resolve(Path) only works for same Path type
+				Files.walkFileTree(src, EnumSet.of(FOLLOW_LINKS), Integer.MAX_VALUE, new SimpleFileVisitor<>() {
+					@Override
+					public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attr) throws IOException {
+						Files.createDirectories(dest.resolve(src.relativize(dir)));
+						return FileVisitResult.CONTINUE;
+					}
+					@Override
+					public FileVisitResult visitFile(Path file, BasicFileAttributes attr) throws IOException {
+						Files.copy(file, dest.resolve(src.relativize(file)), StandardCopyOption.REPLACE_EXISTING);
+						return FileVisitResult.CONTINUE;
+					}
+				});
+			}
+			else {  // use dest.resolve(String) for different Path types
+				Files.walkFileTree(src, EnumSet.of(FOLLOW_LINKS), Integer.MAX_VALUE, new SimpleFileVisitor<>() {
+					@Override
+					public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attr) throws IOException {
+						Files.createDirectories(dest.resolve(src.relativize(dir).toString()));
+						return FileVisitResult.CONTINUE;
+					}
+					@Override
+					public FileVisitResult visitFile(Path file, BasicFileAttributes attr) throws IOException {
+						Files.copy(file, dest.resolve(src.relativize(file).toString()), StandardCopyOption.REPLACE_EXISTING);
+						return FileVisitResult.CONTINUE;
+					}
+				});
+			}
 		}
 		else if (srcAttr.isRegularFile()) {
 			Files.copy(src, dest);

spring-core/src/test/java/org/springframework/util/FileSystemUtilsTests.java

@@ -17,20 +17,29 @@
 package org.springframework.util;
 
 import java.io.File;
+import java.net.URI;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.util.Map;
 
-import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
+ * Tests for {@link FileSystemUtils}.
+ *
  * @author Rob Harrop
+ * @author Sam Brannen
+ * @author Juergen Hoeller
  */
 class FileSystemUtilsTests {
 
 	@Test
-	void deleteRecursively() throws Exception {
-		File root = new File("./tmp/root");
+	void deleteRecursively(@TempDir File tempDir) throws Exception {
+		File root = new File(tempDir, "root");
 		File child = new File(root, "child");
 		File grandchild = new File(child, "grandchild");
 
@@ -53,8 +62,8 @@ void deleteRecursively() throws Exception {
 	}
 
 	@Test
-	void copyRecursively() throws Exception {
-		File src = new File("./tmp/src");
+	void copyRecursively(@TempDir File tempDir) throws Exception {
+		File src = new File(tempDir, "src");
 		File child = new File(src, "child");
 		File grandchild = new File(child, "grandchild");
 
@@ -68,27 +77,25 @@ void copyRecursively() throws Exception {
 		assertThat(grandchild).exists();
 		assertThat(bar).exists();
 
-		File dest = new File("./dest");
+		File dest = new File(tempDir, "/dest");
 		FileSystemUtils.copyRecursively(src, dest);
 
 		assertThat(dest).exists();
-		assertThat(new File(dest, child.getName())).exists();
+		assertThat(new File(dest, "child")).exists();
+		assertThat(new File(dest, "child/bar.txt")).exists();
 
-		FileSystemUtils.deleteRecursively(src);
-		assertThat(src).doesNotExist();
-	}
+		URI uri = URI.create("jar:file:/" + dest.toString().replace('\\', '/') + "/archive.zip");
+		Map<String, String> env = Map.of("create", "true");
+		FileSystem zipfs = FileSystems.newFileSystem(uri, env);
+		Path ziproot = zipfs.getPath("/");
+		FileSystemUtils.copyRecursively(src.toPath(), ziproot);
 
+		assertThat(zipfs.getPath("/child")).exists();
+		assertThat(zipfs.getPath("/child/bar.txt")).exists();
 
-	@AfterEach
-	void tearDown() {
-		File tmp = new File("./tmp");
-		if (tmp.exists()) {
-			FileSystemUtils.deleteRecursively(tmp);
-		}
-		File dest = new File("./dest");
-		if (dest.exists()) {
-			FileSystemUtils.deleteRecursively(dest);
-		}
+		zipfs.close();
+		FileSystemUtils.deleteRecursively(src);
+		assertThat(src).doesNotExist();
 	}
 
 }

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

@@ -203,8 +203,8 @@ private static Mono<Void> zeroCopy(Resource resource, @Nullable ResourceRegion r
 				}
 				return zeroCopyHttpOutputMessage.writeWith(file, pos, count);
 			}
-			catch (IOException ex) {
-				// should not happen
+			catch (IOException | UnsupportedOperationException ignore) {
+				// returning null below leads to fallback code path
 			}
 		}
 		return null;