javaNIO中关于ByteBuffer的用法

 public static ByteBuffer allocate(int capacity) {
        if (capacity < 0)
            throw new IllegalArgumentException();
        return new HeapByteBuffer(capacity, capacity);
    }
 public static ByteBuffer wrap(byte[] array,
                                    int offset, int length)
 {
    try {
         return new HeapByteBuffer(array, offset, length);
    } catch (IllegalArgumentException x) {
            throw new IndexOutOfBoundsException();
     }
  }

 public final Buffer flip() {
        limit = position;
        position = 0;
        mark = -1;
        return this;
    }

 public final Buffer clear() {
        position = 0;
        limit = capacity;
        mark = -1;
        return this;
    }

 public final Buffer mark() {
        mark = position;
        return this;
    }
 public final Buffer reset() {
        int m = mark;
        if (m < 0)
            throw new InvalidMarkException();
        position = m;
        return this;
    }

public void test() throws IOException
    {
        ByteBuffer buff = ByteBuffer.allocate(256);
        FileChannel in = null;
        FileChannel out = null;
        try
        {
            in = new FileInputStream("filein").getChannel();
            out = new FileOutputStream("fileout").getChannel();
            while(fin.read(buff) != -1) {
                buff.flip();
                fout.write(buff);
                buff.clear();
            }
        }
        catch (FileNotFoundException e)
        {
            throw e;
        } finally {
            try {
                if(in != null) {
                    in.close();
                }
                if(fout != null) {
                    out.close();
                }
            } catch(IOException e) {
                throw e;
            }
        }
    }

IsoFile isoFile = new IsoFile("文件路径");