ByteBuffer使用方法

position 当前读或写位置

limit限制

capacity容量

1、rewind() 数据不变 position = 0 ; limit = limit; capatiy = capatiy

2、clear()  数据清空  position = 0 ; limit = capatiy; capatiy = capatiy

3、position(int); 设置position位置

4、get(byte[] b, s, e);获取从s处读取e个byte，position = s+e;limit = limit; capatiy = capatiy

5、flip(); limit = positoon ;positoon = 0;  capatiy = capatiy