字节流:

InputStream ​ FileInputStream ​ FilterInputStream ​ BufferedInputStream ​ CheckedInputSteam ​ CipherInputStream ​ DataInputStream ​ DigestInoutStream

outputStream
    FileOutputStream
    BufferedOutputStream

字符流:

Reader ​ BufferedReader ​ FileReader ​ FilterReader ​ PushbackReader ​ PipedReader ​ CharArrayReader ​ StringReader ​ InputStringReader

Writer
    FileWriter
    BufferedWriter
    PrintWriter
    FileWriter
    FilterWriter
    PipedWriter
    CharArrayWriter
    StringWriter
    OutputStreamWriter

对象流:

序列化: 将内存中的对象写入到磁盘中 ​ 反序列化: 将磁盘中的对象读取到内存中 ​

被序列化的实体类 ,必须实现Serializable接口 目的是为了jvm能够识别
​
对象输入流
ObjectInputStream
    方法: Object readObject() 
对象输出流
objectOutputStream
    void writeObject(Object obj);

​ ​ ​ ​ ​ ​