（1）字节输入流
基类：InputStream
FileInputStream、ByteArrayInputStream、PipedInputStream、BufferedInputStream、ObjectInputStream、FilterInputStream、PushbackInputStream、DataInputStream
（2）字节输出流
基类：OutputStream
FileOutputStream、ByteArrayOutputStream、PipedOutputStream、BufferedOutputStream、ObjectOutputStream、FilterOutputStream、PrintStream、DataOutputStream
（3）字符输入流
基类：Reader
FileReader、CharArrayReader、PipedReader、StringReader、BufferedReader、InputStreamReader、FilterReader、PushbackReader
（4）字符输出流
基类：Writer
FileWriter、CharArrayWriter、PipedWriter、StringWriter、BufferedWriter、OutputStreamWriter、FilterWriter、PrintWriter