9.2、流的分类

* 一.流的分类
* 1.操作数据的单位 字节流 字符流
* 2.数据的流向 输入流 输出流
* 3.流的角色 节点流 处理流
*
* 二.流的体系结构
* 抽象基类 节点流(文件流) 缓冲流（处理流的一种）
* InputStream FileInputStream(read(byte[] buffer)) BufferedInputStream(read(byte[] buffer))
* OutputStream FileOutputStream(write(byte[] buffer,0,len)) BufferedOutputStream(write(byte[] buffer,0,len))
* Reader FileReader(read(byte[] cbuf)) BufferedReader(read(byte[] cbuf / readLine()))
* Whiter FileWriter(write(byte[] cbuf,0,len)) BufferedWriter(write(byte[] cbuf,0,len))