IO流 字节流的缓冲区

package com.yyq;
/*
 * 字节流的缓冲区
 */
import java.io.*;
public class CopyMP3 {
    public static void main(String[] args) throws Exception {
        long start = System.currentTimeMillis();
        copy_1();
        long end = System.currentTimeMillis();
        System.out.println(end-start);
    }
    public static void copy_1() throws Exception{
        BufferedInputStream bufis = new BufferedInputStream(
                new FileInputStream("1.jpg"));
        BufferedOutputStream bufos = new BufferedOutputStream(
                new FileOutputStream("2.jpg"));
        byte[] buf = new byte[1024];
        int num = 0;
        while((num = bufis.read(buf))!=-1){
            bufos.write(buf);
        }
    }
}