java.io

 数据传输方式区分
                字节流(InputStream,OutputStream)
        字符流(Reader,Writer)
    功能区分
        文件流(FileInputStream FileOutputStream FileReader FileWriter)
        数组流(ByteArrayInputStream ByteArrayOutputStream CharArrayReader CharArrayWriter)
        管道流(PipedInputStream PipedOutputStream PipedReader PipedWriter)
        基本数据类型(DataInputStream DataOutputStream)
        缓冲(BufferedInputStream BufferedOutputStream BufferedReader BufferedWriter)
        打印(PrintStream PrintWriter)
        对象序列化(ObjectInputStream ObjectOutputStream)
        转换(InputStreamReader OutputStreamWriter)