| /* |
| * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.nio.file; |
| |
| import java.nio.file.attribute.BasicFileAttributes; |
| import java.io.IOException; |
| |
| /** |
| * A visitor of files. An implementation of this interface is provided to the |
| * {@link Files#walkFileTree Files.walkFileTree} methods to visit each file in |
| * a file tree. |
| * |
| * <p> <b>Usage Examples:</b> |
| * Suppose we want to delete a file tree. In that case, each directory should |
| * be deleted after the entries in the directory are deleted. |
| * <pre> |
| * Path start = ... |
| * Files.walkFileTree(start, 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 e) |
| * throws IOException |
| * { |
| * if (e == null) { |
| * Files.delete(dir); |
| * return FileVisitResult.CONTINUE; |
| * } else { |
| * // directory iteration failed |
| * throw e; |
| * } |
| * } |
| * }); |
| * </pre> |
| * <p> Furthermore, suppose we want to copy a file tree to a target location. |
| * In that case, symbolic links should be followed and the target directory |
| * should be created before the entries in the directory are copied. |
| * <pre> |
| * final Path source = ... |
| * final Path target = ... |
| * |
| * Files.walkFileTree(source, EnumSet.of(FileVisitOption.FOLLOW_LINKS), Integer.MAX_VALUE, |
| * new SimpleFileVisitor<Path>() { |
| * @Override |
| * public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) |
| * throws IOException |
| * { |
| * Path targetdir = target.resolve(source.relativize(dir)); |
| * try { |
| * Files.copy(dir, targetdir); |
| * } catch (FileAlreadyExistsException e) { |
| * if (!Files.isDirectory(targetdir)) |
| * throw e; |
| * } |
| * return CONTINUE; |
| * } |
| * @Override |
| * public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) |
| * throws IOException |
| * { |
| * Files.copy(file, target.resolve(source.relativize(file))); |
| * return CONTINUE; |
| * } |
| * }); |
| * </pre> |
| * |
| * @since 1.7 |
| */ |
| |
| public interface FileVisitor<T> { |
| |
| /** |
| * Invoked for a directory before entries in the directory are visited. |
| * |
| * <p> If this method returns {@link FileVisitResult#CONTINUE CONTINUE}, |
| * then entries in the directory are visited. If this method returns {@link |
| * FileVisitResult#SKIP_SUBTREE SKIP_SUBTREE} or {@link |
| * FileVisitResult#SKIP_SIBLINGS SKIP_SIBLINGS} then entries in the |
| * directory (and any descendants) will not be visited. |
| * |
| * @param dir |
| * a reference to the directory |
| * @param attrs |
| * the directory's basic attributes |
| * |
| * @return the visit result |
| * |
| * @throws IOException |
| * if an I/O error occurs |
| */ |
| FileVisitResult preVisitDirectory(T dir, BasicFileAttributes attrs) |
| throws IOException; |
| |
| /** |
| * Invoked for a file in a directory. |
| * |
| * @param file |
| * a reference to the file |
| * @param attrs |
| * the file's basic attributes |
| * |
| * @return the visit result |
| * |
| * @throws IOException |
| * if an I/O error occurs |
| */ |
| FileVisitResult visitFile(T file, BasicFileAttributes attrs) |
| throws IOException; |
| |
| /** |
| * Invoked for a file that could not be visited. This method is invoked |
| * if the file's attributes could not be read, the file is a directory |
| * that could not be opened, and other reasons. |
| * |
| * @param file |
| * a reference to the file |
| * @param exc |
| * the I/O exception that prevented the file from being visited |
| * |
| * @return the visit result |
| * |
| * @throws IOException |
| * if an I/O error occurs |
| */ |
| FileVisitResult visitFileFailed(T file, IOException exc) |
| throws IOException; |
| |
| /** |
| * Invoked for a directory after entries in the directory, and all of their |
| * descendants, have been visited. This method is also invoked when iteration |
| * of the directory completes prematurely (by a {@link #visitFile visitFile} |
| * method returning {@link FileVisitResult#SKIP_SIBLINGS SKIP_SIBLINGS}, |
| * or an I/O error when iterating over the directory). |
| * |
| * @param dir |
| * a reference to the directory |
| * @param exc |
| * {@code null} if the iteration of the directory completes without |
| * an error; otherwise the I/O exception that caused the iteration |
| * of the directory to complete prematurely |
| * |
| * @return the visit result |
| * |
| * @throws IOException |
| * if an I/O error occurs |
| */ |
| FileVisitResult postVisitDirectory(T dir, IOException exc) |
| throws IOException; |
| } |
