Consistent use of NIO.2 for file read/write interactions

Issue: SPR-15748

Author: jhoeller

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

@@ -17,15 +17,16 @@
 package org.springframework.core.io;
 
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.URI;
 import java.net.URL;
 import java.net.URLConnection;
+import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
+import java.nio.file.StandardOpenOption;
 
 import org.springframework.util.ResourceUtils;
 
@@ -127,7 +128,7 @@ protected File getFile(URI uri) throws IOException {
 	@Override
 	public ReadableByteChannel readableChannel() throws IOException {
 		if (isFile()) {
-			return new FileInputStream(getFile()).getChannel();
+			return FileChannel.open(getFile().toPath(), StandardOpenOption.READ);
 		}
 		else {
 			return super.readableChannel();

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

@@ -17,15 +17,16 @@
 package org.springframework.core.io;
 
 import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.URI;
 import java.net.URL;
+import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.WritableByteChannel;
+import java.nio.file.Files;
+import java.nio.file.StandardOpenOption;
 
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -35,9 +36,15 @@
  * Supports resolution as a {@code File} and also as a {@code URL}.
  * Implements the extended {@link WritableResource} interface.
  *
+ * <p>Note: As of Spring Framework 5.0, this {@link Resource} implementation
+ * uses NIO.2 API for read/write interactions. Nevertheless, in contrast to
+ * {@link PathResource}, it primarily manages a {@code java.io.File} handle.
+ *
  * @author Juergen Hoeller
  * @since 28.12.2003
+ * @see PathResource
  * @see java.io.File
+ * @see java.nio.file.Files
  */
 public class FileSystemResource extends AbstractResource implements WritableResource {
 
@@ -113,7 +120,7 @@ public boolean isReadable() {
 	 */
 	@Override
 	public InputStream getInputStream() throws IOException {
-		return new FileInputStream(this.file);
+		return Files.newInputStream(this.file.toPath());
 	}
 
 	/**
@@ -133,7 +140,7 @@ public boolean isWritable() {
 	 */
 	@Override
 	public OutputStream getOutputStream() throws IOException {
-		return new FileOutputStream(this.file);
+		return Files.newOutputStream(this.file.toPath());
 	}
 
 	/**
@@ -176,7 +183,7 @@ public File getFile() {
 	 */
 	@Override
 	public ReadableByteChannel readableChannel() throws IOException {
-		return new FileInputStream(this.file).getChannel();
+		return FileChannel.open(getFile().toPath(), StandardOpenOption.READ);
 	}
 
 	/**
@@ -185,7 +192,7 @@ public ReadableByteChannel readableChannel() throws IOException {
 	 */
 	@Override
 	public WritableByteChannel writableChannel() throws IOException {
-		return new FileOutputStream(this.file).getChannel();
+		return FileChannel.open(getFile().toPath(), StandardOpenOption.WRITE);
 	}
 
 	/**

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

@@ -41,7 +41,9 @@
  * @author Philippe Marschall
  * @author Juergen Hoeller
  * @since 4.0
+ * @see FileSystemResource
  * @see java.nio.file.Path
+ * @see java.nio.file.Files
  */
 public class PathResource extends AbstractResource implements WritableResource {
 
@@ -52,8 +54,7 @@ public class PathResource extends AbstractResource implements WritableResource {
 	 * Create a new PathResource from a Path handle.
 	 * <p>Note: Unlike {@link FileSystemResource}, when building relative resources
 	 * via {@link #createRelative}, the relative path will be built <i>underneath</i>
-	 * the given root:
-	 * e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"!
+	 * the given root: e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"!
 	 * @param path a Path handle
 	 */
 	public PathResource(Path path) {
@@ -65,8 +66,7 @@ public PathResource(Path path) {
 	 * Create a new PathResource from a Path handle.
 	 * <p>Note: Unlike {@link FileSystemResource}, when building relative resources
 	 * via {@link #createRelative}, the relative path will be built <i>underneath</i>
-	 * the given root:
-	 * e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"!
+	 * the given root: e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"!
 	 * @param path a path
 	 * @see java.nio.file.Paths#get(String, String...)
 	 */
@@ -79,8 +79,7 @@ public PathResource(String path) {
 	 * Create a new PathResource from a Path handle.
 	 * <p>Note: Unlike {@link FileSystemResource}, when building relative resources
 	 * via {@link #createRelative}, the relative path will be built <i>underneath</i>
-	 * the given root:
-	 * e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"!
+	 * the given root: e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"!
 	 * @see java.nio.file.Paths#get(URI)
 	 * @param uri a path URI
 	 */
@@ -193,7 +192,7 @@ public File getFile() throws IOException {
 		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");
+			throw new FileNotFoundException(this.path + " cannot be resolved to absolute file path");
 		}
 	}
 
@@ -231,11 +230,11 @@ public long contentLength() throws IOException {
 	public long lastModified() throws IOException {
 		// We can not use the superclass method since it uses conversion to a File and
 		// only a Path on the default file system can be converted to a File...
-		return Files.getLastModifiedTime(path).toMillis();
+		return Files.getLastModifiedTime(this.path).toMillis();
 	}
 
 	/**
-	 * This implementation creates a FileResource, applying the given path
+	 * This implementation creates a PathResource, applying the given path
 	 * relative to the path of the underlying file of this resource descriptor.
 	 * @see java.nio.file.Path#resolve(String)
 	 */

spring-core/src/main/java/org/springframework/util/FileCopyUtils.java

@@ -16,19 +16,16 @@
 
 package org.springframework.util;
 
-import java.io.BufferedInputStream;
-import java.io.BufferedOutputStream;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.Reader;
 import java.io.StringWriter;
 import java.io.Writer;
+import java.nio.file.Files;
 
 import org.springframework.lang.Nullable;
 
@@ -42,6 +39,7 @@
  * @author Juergen Hoeller
  * @since 06.10.2003
  * @see StreamUtils
+ * @see FileSystemUtils
  */
 public abstract class FileCopyUtils {
 
@@ -62,9 +60,7 @@ public abstract class FileCopyUtils {
 	public static int copy(File in, File out) throws IOException {
 		Assert.notNull(in, "No input File specified");
 		Assert.notNull(out, "No output File specified");
-
-		return copy(new BufferedInputStream(new FileInputStream(in)),
-				new BufferedOutputStream(new FileOutputStream(out)));
+		return copy(Files.newInputStream(in.toPath()), Files.newOutputStream(out.toPath()));
 	}
 
 	/**
@@ -76,10 +72,7 @@ public static int copy(File in, File out) throws IOException {
 	public static void copy(byte[] in, File out) throws IOException {
 		Assert.notNull(in, "No input byte array specified");
 		Assert.notNull(out, "No output File specified");
-
-		ByteArrayInputStream inStream = new ByteArrayInputStream(in);
-		OutputStream outStream = new BufferedOutputStream(new FileOutputStream(out));
-		copy(inStream, outStream);
+		copy(new ByteArrayInputStream(in), Files.newOutputStream(out.toPath()));
 	}
 
 	/**
@@ -90,8 +83,7 @@ public static void copy(byte[] in, File out) throws IOException {
 	 */
 	public static byte[] copyToByteArray(File in) throws IOException {
 		Assert.notNull(in, "No input File specified");
-
-		return copyToByteArray(new BufferedInputStream(new FileInputStream(in)));
+		return copyToByteArray(Files.newInputStream(in.toPath()));
 	}
 
 

spring-core/src/main/java/org/springframework/util/FileSystemUtils.java

@@ -18,6 +18,11 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
 
 import org.springframework.lang.Nullable;
 
@@ -27,29 +32,60 @@
  * @author Rob Harrop
  * @author Juergen Hoeller
  * @since 2.5.3
- * @deprecated as of Spring Framework 5.0, in favor of native NIO API usage
+ * @see java.io.File
+ * @see java.nio.file.Path
+ * @see java.nio.file.Files
  */
-@Deprecated
 public abstract class FileSystemUtils {
 
 	/**
 	 * Delete the supplied {@link File} - for directories,
 	 * recursively delete any nested directories or files as well.
+	 * <p>Note: Like {@link File#delete()}, this method does not throw any
+	 * exception but rather silently returns {@code false} in case of I/O
+	 * errors. Consider using {@link #deleteRecursively(Path)} for NIO-style
+	 * handling of I/O errors, clearly differentiating between non-existence
+	 * and failure to delete an existing file.
 	 * @param root the root {@code File} to delete
-	 * @return {@code true} if the {@code File} was deleted,
+	 * @return {@code true} if the {@code File} was successfully deleted,
 	 * otherwise {@code false}
 	 */
 	public static boolean deleteRecursively(@Nullable File root) {
-		if (root != null && root.exists()) {
-			if (root.isDirectory()) {
-				File[] children = root.listFiles();
-				if (children != null) {
-					for (File child : children) {
-						deleteRecursively(child);
-					}
-				}
+		if (root != null) {
+			try {
+				return deleteRecursively(root.toPath());
+			}
+			catch (IOException ex) {
+				return false;
 			}
-			return root.delete();
+		}
+		return false;
+	}
+
+	/**
+	 * Delete the supplied {@link File} - for directories,
+	 * recursively delete any nested directories or files as well.
+	 * @param root the root {@code File} to delete
+	 * @return {@code true} if the {@code File} existed and was deleted,
+	 * or {@code false} it it did not exist
+	 * @throws IOException in the case of I/O errors
+	 * @since 5.0
+	 */
+	public static boolean deleteRecursively(@Nullable Path root) throws IOException {
+		if (root != null) {
+			Files.walkFileTree(root, new SimpleFileVisitor<Path>() {
+				@Override
+				public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+					Files.delete(file);
+					return FileVisitResult.CONTINUE;
+				}
+				@Override
+				public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+					Files.delete(dir);
+					return FileVisitResult.CONTINUE;
+				}
+			});
+			return Files.deleteIfExists(root);
 		}
 		return false;
 	}
@@ -61,43 +97,44 @@ public static boolean deleteRecursively(@Nullable File root) {
 	 * @param dest the destination directory
 	 * @throws IOException in the case of I/O errors
 	 */
-	public static void copyRecursively(@Nullable File src, File dest) throws IOException {
-		Assert.isTrue(src != null && (src.isDirectory() || src.isFile()),
-				"Source File must denote a directory or file");
+	public static void copyRecursively(File src, File dest) throws IOException {
+		Assert.notNull(src, "Source File must not be null");
 		Assert.notNull(dest, "Destination File must not be null");
-		doCopyRecursively(src, dest);
+		copyRecursively(src.toPath(), dest.toPath());
 	}
 
 	/**
-	 * Actually copy the contents of the {@code src} file/directory
+	 * Recursively copy the contents of the {@code src} file/directory
 	 * to the {@code dest} file/directory.
 	 * @param src the source directory
 	 * @param dest the destination directory
 	 * @throws IOException in the case of I/O errors
+	 * @since 5.0
 	 */
-	private static void doCopyRecursively(File src, File dest) throws IOException {
-		if (src.isDirectory()) {
-			dest.mkdir();
-			File[] entries = src.listFiles();
-			if (entries == null) {
-				throw new IOException("Could not list files in directory: " + src);
-			}
-			for (File entry : entries) {
-				doCopyRecursively(entry, new File(dest, entry.getName()));
-			}
+	public static void copyRecursively(Path src, Path dest) throws IOException {
+		Assert.notNull(src, "Source Path must not be null");
+		Assert.notNull(dest, "Destination Path must not be null");
+		BasicFileAttributes srcAttr = Files.readAttributes(src, BasicFileAttributes.class);
+
+		if (srcAttr.isDirectory()) {
+			Files.walkFileTree(src, new SimpleFileVisitor<Path>() {
+				@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)));
+					return FileVisitResult.CONTINUE;
+				}
+			});
 		}
-		else if (src.isFile()) {
-			try {
-				dest.createNewFile();
-			}
-			catch (IOException ex) {
-				throw new IOException("Failed to create file: " + dest, ex);
-			}
-			FileCopyUtils.copy(src, dest);
+		else if (srcAttr.isRegularFile()) {
+			Files.copy(src, dest);
 		}
 		else {
-			// Special File handle: neither a file not a directory.
-			// Simply skip it when contained in nested directory...
+			throw new IllegalArgumentException("Source File must denote a directory or file");
 		}
 	}
 

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

@@ -26,7 +26,6 @@
 /**
  * @author Rob Harrop
  */
-@Deprecated
 public class FileSystemUtilsTests {
 
 	@Test