FileVisitor打印目录中包含的所有目录和文件的大小

import java.io.IOException;
/**
n o w j a   v  a . c o m - 时  代  Java 提供 
**/

import java.nio.file.*;

import java.nio.file.attribute.BasicFileAttributes;


/**

 * FileVisitor to print the size of all directories and files contained on the directory

 * passed as an argument to the program, and the accumulated size of everything

 */

public class FileVisitorDirectorySize {

    public static void main(String[] args) throws Exception {

        if (args.length != 1) System.out.println("Use: java FileVisitorDirectorySize <directory>");

        Path root = Paths.get(args[0]);


        CalculateFileSizeVisitor visitor = new CalculateFileSizeVisitor();

        Files.walkFileTree(root, visitor);

        System.out.format("The given directory contains %d files spread in %d directories, occupying %.4f MB in disk", visitor.numFiles, visitor.numDirs, visitor.sizeSum / (1024.0 * 1024));// 来 自 NowJava.com - 时  代  Java

    }

}


class CalculateFileSizeVisitor implements FileVisitor<Path> {

    int numFiles = 0;

    int numDirs = 0;

    long sizeSum = 0;


    @Override

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

        System.out.println("[D] " + dir);

        numDirs++;

        return FileVisitResult.CONTINUE;

    }


    @Override

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

        final long size = attrs.size();

        System.out.println("[F]\t\t " + file + ". Size of the file: " + size);

        sizeSum += size;

        numFiles++;

        return FileVisitResult.CONTINUE;

    }


    @Override

    public FileVisitResult visitFileFailed(Path file, IOException exc) throws