递归将目录和文件复制到目的地

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想要改进此问题吗？添加详细信息并通过

闭合 2年前。

Answer 1

这是一个可以通过 fileVisitor 接口。在这种方法中，可以将代码分为三个部分：

• 目录访问=创建目标目的地目录的空副本。
• 文件访问=在先前访问的目录中复制文件。
• 发布目录访问=打印复制文件夹的总尺寸。

public class FileCopier implements FileVisitor<Path> {

    private final Path sourcePath;
    private final Path targetPath;

    //Map holding the size of each directory
    private final Map<String, Long> mapSize;

    public FileCopier(Path sourcePath, Path targetPath) throws IOException {
        //Check whether the destination directory exists or not
        if (!Files.exists(targetPath)) {
            Files.createDirectories(targetPath);
        }

        this.sourcePath = sourcePath.toRealPath();
        this.targetPath = targetPath.toRealPath();
        this.mapSize = new HashMap<>();
    }

    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
        //Copying the directory first, and then its content (copying a directory does not copy its content)

        //Retrieving the last bit of the folder's path relatively from the source path ("subtracts" the source path)
        Path lastBitPath = sourcePath.relativize(dir.toAbsolutePath().normalize());

        //Adding the last bit to the target path
        Path targetCopyPath = targetPath.resolve(lastBitPath).toAbsolutePath().normalize();

        //Copying the folder is this doesn't exist yet
        if (!Files.exists(targetCopyPath)) {
            Files.copy(dir, targetCopyPath, StandardCopyOption.COPY_ATTRIBUTES);
        }

        //Adding a new key-value pair, where the key is the folder's path, while the value is folder's size in bytes
        mapSize.put(targetCopyPath.toString(), 0L);
        System.out.println("Started: " + targetCopyPath);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
        //Building the new file path by removing the source path from the file, and then adding the result on top of the target path
        Path targetCopyPath = targetPath.resolve(sourcePath.relativize(file.toAbsolutePath().normalize())).toAbsolutePath().normalize();
        Files.copy(file, targetCopyPath, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES);

        //Adding the file's size to the pair's value identified by the folder's path
        mapSize.put(targetCopyPath.getParent().toString(), mapSize.get(targetCopyPath.getParent().toString()) + Files.size(file));
        System.out.println("Finished FILE: " + targetCopyPath);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc) {
        return FileVisitResult.TERMINATE;
    }

    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
        //Printing the folder's size after finishing its copy (visit)

        //Retrieving the last bit of the folder's path by removing the source location
        Path lastBitPath = sourcePath.relativize(dir.toAbsolutePath().normalize());

        //Adding the last bit of the folder's path on top of the target path
        Path targetCopyPath = targetPath.resolve(lastBitPath).toAbsolutePath().normalize();

        //Showing the number of bytes corresponded to the copied directory
        System.out.println("Total " + this.mapSize.get(targetCopyPath.toString()) + " bytes were copied into " + targetCopyPath);
        return FileVisitResult.CONTINUE;
    }

    public static void main(String[] args) throws IOException {
        Path sourcePath = Paths.get("./test1");
        Path targetPath = Paths.get("./test2");
        FileCopier fc = new FileCopier(sourcePath, targetPath);
        Files.walkFileTree(sourcePath, fc);
    }
}