求大佬解一下

package com.huawei.test;

import import import import import java.nio.channels.FileChannel;

public class FileUtil {
    public static void main(String[] args) throws IOException {
        File src = new File ("D:\\kstest");
        File dest = new File("D:\\pictures");
        copy(src, dest);
    }
    private static void copy(File src, File dest) {
        if(src.isDirectory()) {
            if(!dest.isDirectory()) {
                dest.mkdirs();
            }
            for(File file:src.listFiles()) {
                copy(file, new File(dest, file.getName()));
            }
        } else if(src.isFile()) {
            fileChannelCopy(src, dest);
        }
    }
    public static void fileChannelCopy(File srcFile, File dstFile) {
        FileInputStream fileInputStream = null;
        FileOutputStream fileOutputStream = null;
        FileChannel inputChannel = null;
        FileChannel outputChannel = null;
        try {
            fileInputStream = new FileInputStream(srcFile);
            fileOutputStream = new FileOutputStream(dstFile);
            inputChannel = fileInputStream.getChannel();
            outputChannel = fileOutputStream.getChannel();
            inputChannel.transferTo(0, inputChannel.size(), outputChannel);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                fileInputStream.close();
                inputChannel.close();
                fileOutputStream.close();
                outputChannel.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}