Java.io.InputStream.read（）方法将每个数据类型读取为字节吗？

Question

if the read method reads a byte of data from the input stream, when it has to read a char, does it read twice byte by byte? as a char is of 2 byes?

Answer 1

InputStream operates on bytes. It is the underlying I/O abstraction in Java. It can read a single byte or a sequence of bytes, depending on what the caller requests. But it knows nothing about characters, so it cannot, by itself, decide to read two bytes for a character. A Reader would have to request this.

If you need to read characters, use Reader to read them from the InputStream .

(Similarly, to read serialized Java objects, you would use ObjectInputStream , which again reads them from the InputStream . Or you can use Scanner to read a variety of inputs from numbers to text, again from an InputStream .)

The purpose of this abstraction is separation of responsibilities -

• The InputStream provides a stream of bytes and handles all underlying logic (file reading / network / ...).
• The Reader converts the stream of bytes to stream of characters, and doesn't care where the data came from.

Answer 2

根据在线提供的Oracle文档https://docs.oracle.com/javase/7/docs/api/java/io/InputStream.html#read（），它读取字节数组