字节流：InputStream（new FileInputStream（new File()）;
Outpustream（new FileOutputStream（new File()）;
字符流: Reader (new FileReader(new File);
Writer(new FileWriter(new File);
内存操作流：ByteArrayInputStream; ByteArrayOutputStream;
打印流：PrintStream,PrintWriter.
字符缓冲流：BufferedReader,BufferedWriter
数据操作流：DataInputStream,DataOutputStream
对象序列化：ObjectInputStream，ObjectOutputStream.