FileCopier.java

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package net.krazyweb.helpers;

import static java.nio.file.FileVisitResult.CONTINUE;
import static java.nio.file.FileVisitResult.SKIP_SUBTREE;
import static java.nio.file.StandardCopyOption.COPY_ATTRIBUTES;
import static java.nio.file.StandardCopyOption.REPLACE_EXISTING;

import java.io.IOException;
import java.nio.file.CopyOption;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.FileSystemLoopException;
import java.nio.file.FileVisitResult;
import java.nio.file.FileVisitor;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.FileTime;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;


/**
 * Sample code that copies files in a similar manner to the cp(1) program.
 */

public class FileCopier {
	
	private static final Logger log = LogManager.getLogger(FileCopier.class);

	/**
	 * Copy source file to target location. If {@code prompt} is true then
	 * prompt user to overwrite target if it exists. The {@code preserve}
	 * parameter determines if file attributes should be copied/preserved.
	 */
	private static void copyFile(Path source, Path target, boolean prompt, boolean preserve) {
		
		CopyOption[] options = (preserve) ? new CopyOption[] { COPY_ATTRIBUTES,	REPLACE_EXISTING } : new CopyOption[] { REPLACE_EXISTING };
		
		try {
			Files.createDirectories(target.getParent());
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		try {
			Files.copy(source, target, options);
		} catch (IOException x) {
			log.error(String.format("Unable to copy: %s: %n", source), x);
		}
		
	}

	/**
	 * A {@code FileVisitor} that copies a file-tree ("cp -r")
	 */
	public static class TreeCopier implements FileVisitor<Path> {
		private final Path source;
		private final Path target;
		private final boolean prompt;
		private final boolean preserve;

		TreeCopier(Path source, Path target, boolean prompt, boolean preserve) {
			this.source = source;
			this.target = target;
			this.prompt = prompt;
			this.preserve = preserve;
		}

		@Override
		public FileVisitResult preVisitDirectory(Path dir,
				BasicFileAttributes attrs) {
			// before visiting entries in a directory we copy the directory
			// (okay if directory already exists).
			CopyOption[] options = (preserve) ? new CopyOption[] { COPY_ATTRIBUTES }
					: new CopyOption[0];

			Path newdir = target.resolve(source.relativize(dir));
			try {
				if (Files.notExists(target.getParent())) {
					Files.createDirectories(target.getParent());
				}
				Files.copy(dir, newdir, options);
			} catch (FileAlreadyExistsException x) {
				// ignore
			} catch (IOException x) {
				log.error(String.format("Unable to create: %s%n", newdir), x);
				return SKIP_SUBTREE;
			}
			return CONTINUE;
		}

		@Override
		public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
			copyFile(file, target.resolve(source.relativize(file)), prompt,
					preserve);
			return CONTINUE;
		}

		@Override
		public FileVisitResult postVisitDirectory(Path dir, IOException exc) {
			// fix up modification time of directory when done
			if (exc == null && preserve) {
				Path newdir = target.resolve(source.relativize(dir));
				try {
					FileTime time = Files.getLastModifiedTime(dir);
					Files.setLastModifiedTime(newdir, time);
				} catch (IOException x) {
					log.error(String.format("Unable to copy all attributes to: %s%n", newdir), x);
				}
			}
			return CONTINUE;
		}

		@Override
		public FileVisitResult visitFileFailed(Path file, IOException exc) {
			if (exc instanceof FileSystemLoopException) {
				log.error("cycle detected: " + file);
			} else {
				log.error(String.format("Unable to copy: %s: %s%n", file, exc));
			}
			return CONTINUE;
		}
	}
	
}