Basic Concepts of IO

Division of IO streams

According to the flow direction of the flow, it can be divided into input flow and output flow.
According to the operation unit, it can be divided into byte stream and character stream.
According to the role of the flow, it is divided into node flow and processing flow.
Node Stream: Data can be read and written from or to a specific place (node).Such as FileReader, FileWriter.
Processing stream: It is the connection and encapsulation of an existing stream, and data read and write is realized through the function call of the encapsulated stream.Such as BufferedReader. The constructor that handles streams always takes an additional stream object as a parameter.A stream object is wrapped multiple times by other streams, which is called stream chaining.
Node streams are low-level/low-level streams that connect directly to data sources.A processing stream (wrapper stream) wraps a node stream, which can not only eliminate the implementation differences of different node streams, but also provide a more convenient way to complete input and output.The processing flow wraps the node flow, mainly by increasing the buffering method to improve the efficiency of input and output, using the decorator design pattern, and will not be directly connected to the data source.

Main abstract class

InputStream/Reader: The base class for all input streams, InputStream is a byte input stream, and InputReader is a character input stream.
OutputStream/Writer: The base class for all output streams, OutputStream is a byte output stream, and OutputWriter is a character output stream.

Character IO stream

Byte IO stream

For low load, low concurrency applicationsProgram, you can use synchronous blocking IO or BIO to improve the development rate and better maintainability; for high-load, high-concurrency (network) applications, the synchronous non-blocking I/O model NIO should be used for development.AIO (Asynchronous I/O) is an asynchronous non-blocking IO model. It is implemented based on events and callback mechanisms. After the application operation, it will return directly without blocking. When the background processing is completed, the operating system will notify the corresponding thread to perform subsequent operations.