Java：使用 nio Files.copy 移动目录

Question

我是 nio 类的新手，无法将文件目录移动到新创建的目录。

我首先创建 2 个目录：

File sourceDir = new File(sourceDirStr); //this directory already exists
File destDir = new File(destDirectoryStr); //this is a new directory

然后我尝试使用以下方法将现有文件复制到新目录中：

Path destPath = destDir.toPath();
for (int i = 0; i < sourceSize; i++) {
    Path sourcePath = sourceDir.listFiles()[i].toPath();
    Files.copy(sourcePath, destPath.resolve(sourcePath.getFileName()));
}

这会引发以下错误：

Exception in thread "main" java.nio.file.FileSystemException: destDir/Experiment.log: Not a directory

我知道destDir/Experiment.log不是现有目录； 由于Files.copy操作，它应该是一个新文件。 有人能指出我的操作哪里出了问题吗？ 谢谢！

Answer 1

您需要使用 walkFileTree 来复制目录。 如果您在目录上使用 Files.copy，则只会创建一个空目录。

以下代码取自/改编自http://codingjunkie.net/java-7-copy-move/

File src = new File("c:\\temp\\srctest");
File dest = new File("c:\\temp\\desttest");
Path srcPath = src.toPath();
Path destPath = dest.toPath();

Files.walkFileTree(srcPath, new CopyDirVisitor(srcPath, destPath, StandardCopyOption.REPLACE_EXISTING));

public static class CopyDirVisitor extends SimpleFileVisitor<Path>
{
    private final Path fromPath;
    private final Path toPath;
    private final CopyOption copyOption;

    public CopyDirVisitor(Path fromPath, Path toPath, CopyOption copyOption)
    {
        this.fromPath = fromPath;
        this.toPath = toPath;
        this.copyOption = copyOption;
    }

    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException
    {
        Path targetPath = toPath.resolve(fromPath.relativize(dir));
        if( !Files.exists(targetPath) )
        {
            Files.createDirectory(targetPath);
        }
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException
    {
        Files.copy(file, toPath.resolve(fromPath.relativize(file)), copyOption);
        return FileVisitResult.CONTINUE;
    }
}

Answer 2

如果目标目录不存在，只需制作目标目录。

File sourceDir = new File(source); //this directory already exists
File destDir = new File(dest); //this is a new directory
destDir.mkdirs(); // make sure that the dest directory exists

Path destPath = destDir.toPath();
for (File sourceFile : sourceDir.listFiles()) {
    Path sourcePath = sourceFile.toPath();
    Files.copy(sourcePath, destPath.resolve(sourcePath.getFileName()));
}

请注意， sourceDir.listFiles()也将返回目录，您要么不希望递归到该目录，要么忽略这些目录...

Answer 3

这是我将目录从源递归移动到目标的解决方案。 它就像一个魅力。

public static void move(Path source, Path target) throws IOException {

    class FileMover extends SimpleFileVisitor<Path> {
        private Path source;
        private Path target;

        private FileMover(Path source, Path target) {
            this.source = source;
            this.target = target;
        }

        @Override
        public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs) throws IOException {
            Files.move(file, target.resolve(source.relativize(file)),
                StandardCopyOption.REPLACE_EXISTING);
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult preVisitDirectory(final Path dir, final BasicFileAttributes attrs) throws IOException {
            Path newDir = target.resolve(source.relativize(dir));
            try {
                Files.copy(dir, newDir,
                    StandardCopyOption.COPY_ATTRIBUTES,
                    StandardCopyOption.REPLACE_EXISTING);
            } catch (DirectoryNotEmptyException e) {
                // ignore and skip
            }
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult postVisitDirectory(final Path dir, final IOException exc) throws IOException {
            Path newDir = target.resolve(source.relativize(dir));
            FileTime time = Files.getLastModifiedTime(dir);
            Files.setLastModifiedTime(newDir, time);
            Files.delete(dir);
            return FileVisitResult.CONTINUE;
        }
    }

    FileMover fm = new FileMover(source, target);
    EnumSet<FileVisitOption> opts = EnumSet.of(FileVisitOption.FOLLOW_LINKS);

    Files.walkFileTree(source, opts, Integer.MAX_VALUE, fm);
}

Answer 4

for (int i = 0; i < sourceSize; i++) {
    Path sourcePath = sourceDir.listFiles()[i].toPath();
    Files.copy(sourcePath, destPath.resolve(sourcePath.getFileName()));
}

这是非常奇怪的代码。 您已经从某个地方获得了一个文件计数，在sourceSize ，但是您每次迭代都调用listFiles() 。 我本来期望更像这样的：

for (File file : sourceDir.listFiles()) {
    Path sourcePath = file.toPath();
    Files.copy(sourcePath, destPath.resolve(sourcePath.getFileName()));
}