java 缓冲区 java缓冲流读取文件

public class CopyDemo {
    public static void main(String[] args) throws Exception{
        long time1 = System.currentTimeMillis();
        copy4(new File("d:\\ccc.mp4"),new File("e:\\ccc.mp4"));
        long time2 = System.currentTimeMillis();
        System.out.println(time2-time1);
    }
    //1.字节流读写单个字节   太慢了
    public static void copy1(File src,File desc) throws Exception{
        FileInputStream fis = new FileInputStream(src);
        FileOutputStream fos = new FileOutputStream(desc);
        int len = 0;
        while ((len=fis.read())!=-1){
            fos.write(len);
        }
        fos.close();
        fis.close();
    }
    //2.字节流读写字节数组   550
    public static void copy2(File src,File desc) throws Exception{
        FileInputStream fis = new FileInputStream(src);
        FileOutputStream fos = new FileOutputStream(desc);
        int len = 0;
        byte[] b = new byte[1024*10];
        while ((len=fis.read(b))!=-1){
            fos.write(b,0,len);
        }
        fos.close();
        fis.close();
    }
    //3.字节流缓冲区  读写单个字节   4252
    public static void copy3(File src,File desc) throws Exception{
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
        int len = 0;
        while ((len=bis.read())!=-1){
            bos.write(len);
        }
        bis.close();
        bos.close();
    }
    //4.字节流缓冲区读写字节数组   585
    public static void copy4(File src,File desc) throws  Exception{
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
        int len = 0;
        byte[] b = new byte[1024*10];
        while ((len=bis.read(b))!=-1){
            bos.write(b,0,len);
        }
        bos.close();
        bis.close();
    }