Question

这个程序花了太多时间来计算c：/ Windows下的windows目录。如何使它像操作系统一样快，给出了目录的大小。


    import java.io.File;
    import java.util.Scanner;

public class DirectorySize {
    public static void main(String[] args) {
        // Prompt the user to enter a directory or a file
        System.out.println("Enter a directory or a file: ");
        Scanner input = new Scanner(System.in);
        String directory = input.nextLine();

        // Display the size
        System.out.println(getSize(new File(directory)) + " bytes");
    }

    public static long getSize(File file) {
        long size = 0;  // Store total size of all files

        if(file.isDirectory()) {
            File[] files = file.listFiles();    // All files and subdirectories
            for(int i = 0; files != null && i < files.length; i++) {
                size += getSize(files[i]);  // Recursive call
            }
        } else {
            size += file.length();
        }

        return size;
    }
}


public class DirectorySize {
    public static void main(String[] args) {
        // Prompt the user to enter a directory or a file
        System.out.println("Enter a directory or a file: ");
        Scanner input = new Scanner(System.in);
        String directory = input.nextLine();

        // Display the size
        System.out.println(getSize(new File(directory)) + " bytes");
    }

    public static long getSize(File file) {
        long size = 0;  // Store total size of all files

        if(file.isDirectory()) {
            File[] files = file.listFiles();    // All files and subdirectories
            for(int i = 0; files != null && i < files.length; i++) {
                size += getSize(files[i]);  // Recursive call
            }
        } else {
            size += file.length();
        }

        return size;
    }
}

Answer 1

为什么不使用nio api，它比java.io更好，更快一点。如果用下面的代码行替换你的getSize（）函数，你的性能会提高（40％）。

static long getSize(Path startPath) throws IOException {
        final AtomicLong size = new AtomicLong(0);
        Files.walkFileTree(startPath, new SimpleFileVisitor<Path>() {
            @Override
            public FileVisitResult visitFile(Path file,
                    BasicFileAttributes attrs) throws IOException {
                size.addAndGet(attrs.size());
                return FileVisitResult.CONTINUE;
            }

            public FileVisitResult visitFileFailed(Path file, IOException exc)
                    throws IOException {
                // Skip folders that can't be traversed
                System.out.println("skipped: " + file + "e=" + exc);
                return FileVisitResult.CONTINUE;
            }
        });
        return size.get();
    }

Answer 2

尝试使用apache commons-io，你可以从here

获取它

 long size = FileUtils.sizeOfDirectory(new File("C:/Windows"));
 System.out.println("Folder Size: " + size + " bytes");

计算目录或文件的大小

2 个答案: