Introduction of buffer flow

package BufferStream;
/*
 The use of buffer streams 
 */
import org.junit.Test;

import java.io.*;

public class BufferTest {
    /*
     Realize the copy of non text file 
     */
    @Test
    public void BufferedStreamTest() throws IOException {
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
//        1. Document making object 
            File srcFile = new File("hanyang.png");
            File destFile = new File("hangyang2.png");

//        2. Create byte stream 
            FileInputStream fis = new FileInputStream(srcFile);
            FileOutputStream fos = new FileOutputStream(destFile);

//        2.2 Create a buffer stream 
            bis = new BufferedInputStream(fis);
            bos = new BufferedOutputStream(fos);

//        3. Data manipulation 
            byte[] buffer = new byte[5];
            int len ;
            while ((len = bis.read(buffer))!=-1){
                bos.write(buffer,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (bos!=null) {
                    bos.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (bis!=null) {
                    bis.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

//        4. Resources to shut down : Close the outer layer first , Then close the inner layer .  notes ： While closing the outer layer , The inner flow will also be automatically closed 


//        fos.close();
//        fis.close();

    }
}