Java tutorial
/* * 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 * * https://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.util; 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.StandardCopyOption; import java.nio.file.attribute.BasicFileAttributes; import org.springframework.lang.Nullable; /** * Utility methods for working with the file system. * * @author Rob Harrop * @author Juergen Hoeller * @since 2.5.3 * @see java.io.File * @see java.nio.file.Path * @see java.nio.file.Files */ 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 successfully deleted, * otherwise {@code false} */ public static boolean deleteRecursively(@Nullable File root) { if (root == null) { return false; } try { return deleteRecursively(root.toPath()); } catch (IOException ex) { 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) { return false; } if (!Files.exists(root)) { return false; } 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 true; } /** * 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 */ 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"); copyRecursively(src.toPath(), dest.toPath()); } /** * 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 */ 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)), StandardCopyOption.REPLACE_EXISTING); return FileVisitResult.CONTINUE; } }); } else if (srcAttr.isRegularFile()) { Files.copy(src, dest); } else { throw new IllegalArgumentException("Source File must denote a directory or file"); } } }