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);
}
}
}