（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