多个线程对象，复制同一个文件

利用多个线程可实现对文件的复制效率更高（小文件复制）
大文件复制还是采用单线程复制稳妥；

public class MyTest2 {

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

        new CopyThread(0).start();
        new CopyThread(1024*1024*2).start();
        new CopyThread(1024*1024*4).start();
        new CopyThread(1024*1024*6).start();
        new CopyThread(1024*1024*8).start();
    }

}

class CopyThread extends Thread{
    int filepointer;
    public CopyThread(int filepointer) {
        this.filepointer=filepointer;
    }

    @Override
    public void run() {
        try {

            File sourcefile = new File("C:\\Users\\Administrator\\Desktop\\test\\许巍-歌曲大联唱.mp3");
            File targetfile = new File("C:\\Users\\Administrator\\Desktop\\test\\许巍-歌曲大联唱copy.mp3");
            CopyFile(filepointer, sourcefile, targetfile);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void CopyFile(long filepointer, File sourcefile, File targetfile) throws IOException {

            RandomAccessFile read= new RandomAccessFile(sourcefile,"rw");
            RandomAccessFile write = new RandomAccessFile(targetfile, "rw");
            int len=0;
            byte[] bytes = new byte[0];
            bytes=new byte[1024*1024*2];
            read.seek(filepointer);
            write.seek(filepointer);
            len=read.read(bytes);
            write.write(bytes,0,len);

            filepointer = read.getFilePointer();
            System.out.println(filepointer);
            read.close();
            write.close();

    }
}