com.google.cloud.tools.io.FileUtil Maven / Gradle / Ivy

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/*
 * Copyright 2016 Google LLC.
 *
 * 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
 *
 *     http://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 com.google.cloud.tools.io;

import com.google.common.annotations.Beta;
import com.google.common.base.Preconditions;
import java.io.IOException;
import java.nio.file.CopyOption;
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 java.util.Collections;
import java.util.List;

/** File utilities. */
@Beta
public class FileUtil {

  /**
   * Implementation of recursive directory copy, does NOT overwrite.
   *
   * @param source an existing source directory to copy from
   * @param destination an existing destination directory to copy to
   * @throws IllegalArgumentException if source directory is same destination directory, either
   *     source or destination is not a directory, or destination is inside source
   */
  public static void copyDirectory(final Path source, final Path destination) throws IOException {
    copyDirectory(source, destination, Collections.emptyList());
  }

  /**
   * Implementation of recursive directory copy, does NOT overwrite.
   *
   * @param source an existing source directory to copy from
   * @param destination an existing destination directory to copy to
   * @param excludes a list of paths in "source" to exclude
   * @throws IllegalArgumentException if source directory is same destination directory, either
   *     source or destination is not a directory, or destination is inside source
   */
  public static void copyDirectory(final Path source, final Path destination, List excludes)
      throws IOException {
    Preconditions.checkNotNull(source);
    Preconditions.checkNotNull(destination);
    Preconditions.checkArgument(Files.isDirectory(source), "Source is not a directory");
    Preconditions.checkArgument(Files.isDirectory(destination), "Destination is not a directory");
    Preconditions.checkArgument(
        !Files.isSameFile(source, destination), "Source and destination are the same");
    Preconditions.checkArgument(
        !destination.toAbsolutePath().startsWith(source.toAbsolutePath()),
        "destination is child of source");

    Files.walkFileTree(
        source,
        new SimpleFileVisitor() {
          final CopyOption[] copyOptions = new CopyOption[] {StandardCopyOption.COPY_ATTRIBUTES};

          @Override
          public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
              throws IOException {

            if (dir.equals(source)) {
              return FileVisitResult.CONTINUE;
            }

            if (excludes.contains(dir)) {
              return FileVisitResult.SKIP_SUBTREE;
            }

            Files.copy(dir, destination.resolve(source.relativize(dir)), copyOptions);
            return FileVisitResult.CONTINUE;
          }

          @Override
          public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
              throws IOException {

            if (excludes.contains(file)) {
              return FileVisitResult.CONTINUE;
            }

            Files.copy(file, destination.resolve(source.relativize(file)), copyOptions);
            return FileVisitResult.CONTINUE;
          }
        });
  }
}