java nio 複製文件功能

 

package com.ghb.crp.file;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class FileCopy {
    public static String src = "f://ss.rmvb";
    public static String dist = "f://ss2.rmvb";

    /**
     * @param args
     */
    public static void main(String[] args) {
        long start = System.currentTimeMillis();
        copyNew();
        long end = System.currentTimeMillis();
        System.out.println("nio 用時： " + (end - start));

        long start2 = System.currentTimeMillis();
        copyOld();
        end = System.currentTimeMillis();
        System.out.println("io 用時： " + (end - start2));
    }

    public static void copyOld() {
        File srcFile = new File(src);
        File distFile = new File(dist);
        if (distFile.exists()) {
            distFile.delete();
        }
        try {
            FileInputStream fin = new FileInputStream(srcFile);
            BufferedInputStream buffIn = new BufferedInputStream(fin);

            FileOutputStream fout = new FileOutputStream(distFile);
            BufferedOutputStream buffout = new BufferedOutputStream(fout);
            byte[] bytes = new byte[1024];
            while (buffIn.read(bytes) > 0) {
                buffout.write(bytes);
            }
            fin.close();
            buffIn.close();
            fout.close();
            buffout.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public static void copyNew() {
        try {
            File srcFile = new File(src);
            File distFile = new File(dist);
            if (distFile.exists()) {
                distFile.delete();
            }

            FileInputStream fin = new FileInputStream(srcFile);
            FileOutputStream fout = new FileOutputStream(distFile);
            FileChannel inChannel = fin.getChannel();
            FileChannel outChannel = fout.getChannel();
            int ByteBufferSize = 1024 * 100;
            ByteBuffer buff = ByteBuffer.allocate(ByteBufferSize);

            while (inChannel.read(buff) > 0) {
                buff.flip();
                if (inChannel.position() == inChannel.size()) {// 判斷是不是最後一段數據
                    int lastRead = (int) (inChannel.size() % ByteBufferSize);
                    byte[] bytes = new byte[lastRead];
                    buff.get(bytes, 0, lastRead);
                    outChannel.write(ByteBuffer.wrap(bytes));
                    buff.clear();
                } else {
                    outChannel.write(buff);
                    buff.clear();
                }
            }// 這個使用FileChannel 自帶的複製
            // outChannel.transferFrom(inChannel, 0, inChannel.size());
            outChannel.close();
            inChannel.close();
            fin.close();
            fout.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}