This article is not intended to systematically introduce Java's I / O flow mechanism, only for personal notes

As a java small dish, every time I search other people's Java reading and writing files on the Internet, I always feel confused. Why do I have to declare so many classes and rules? They are totally divided into two categories, so I have a little understanding with questions;

In Java, there are two types of I / O mode classes: InputStream & OutputStream and Reader & writer. In addition, there is a class that processes files and folders;

The input and output stream class of Java adopts the decorator mode, and many other classes are derived from the above five classes. Here is a picture found on the Internet. Let's feel it

Java supports many types of input sources and output terminals, but I'm not going to expand here. I just want to talk about the reading and output of files. As we all know, computer access to external devices is very time-consuming, while access to buffer is very fast. Therefore, in order to improve the efficiency of reading and writing files, in addition to the necessary read-write mechanism between the program and the stream node, buffer mechanism should also be added.

Specific examples are as follows:

package com.practise.test;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStreamWriter;
import java.io.BufferedWriter;
//All with Stream The classes at the end are byte oriented FileInputStream/FileOutputStream
//with Reader/Writer The class at the end is character oriented
//with File The first class is external storage oriented
//with Buffered The first class is buffer oriented
public class ReadAndWrite 
{
    public static void main (String[] args)
    {
        String path = "D:\\Coding\\Java\\TestJava\\testdata\\";
        try {
            File inFile = new File(path + "in.txt");
            File outFile = new File(path + "out.txt");
            InputStreamReader inSr = new InputStreamReader( new FileInputStream(inFile));
            BufferedReader inBr = new BufferedReader(inSr);
            
            OutputStreamWriter outSw = new OutputStreamWriter( new FileOutputStream(outFile));
            BufferedWriter outBw = new BufferedWriter(outSw); 
            
            String line = "";
            while ((line = inBr.readLine()) != null)
            {
                outBw.write(line + "\r\n");
            }
            outBw.close();
            outSw.close();
            inBr.close();
            inSr.close();            
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }        
    }
}