learing java NIO 之 ReadFile

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;

public class ReadFile {
    public static void main(String[] args) {
        try (
                var fis = new FileInputStream("./src/com/serial/ReadFile.java");
                FileChannel fcin = fis.getChannel();)
        {
            ByteBuffer bbuf  = ByteBuffer.allocate();
            while (fcin.read(bbuf)  != -){
                bbuf.flip();
                Charset charset = Charset.forName("GBK");
                CharsetDecoder decoder =  charset.newDecoder();
                CharBuffer cbuf = decoder.decode(bbuf);
                System.out.println(cbuf);
                bbuf.clear();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}