使用SeekableByteChannel从开始到结束复制文件的一部分

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.SeekableByteChannel;

import java.nio.file.Files;// 来 自 N o  w  J a v a . c o m - 时  代  Java

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardOpenOption;

import java.util.EnumSet;


public class Main {

  public static void main(String[] args) {

    Path path = Paths.get("C:/folder1/folder2/folder4", "test.txt");

    ByteBuffer copy = ByteBuffer.allocate(25);

    copy.put("\ntest".getBytes());

    try (SeekableByteChannel seekableByteChannel = (Files.newByteChannel(path,
    /**
    NowJava.com - 时  代  Java 提供 
    **/

        EnumSet.of(StandardOpenOption.READ, StandardOpenOption.WRITE)))) {

      int nbytes;

      do {

        nbytes = seekableByteChannel.read(copy);

      } while (nbytes != -1 && copy.hasRemaining());

      copy.flip();

      seekableByteChannel.positi