IO流24 - 字节流 - 字节流的四种复制文件方式对比

Posted 2020-10-23 清风拂柳

 

package cn.itcast.copy;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/*
 *  文件复制方式,字节流,一共4个方式
 *  1. 字节流读写单个字节                    125250 毫秒
 *  2. 字节流读写字节数组                    193    毫秒  OK
 *  3. 字节流缓冲区流读写单个字节    　　　　　 1210   毫秒
 *  4. 字节流缓冲区流读写字节数组  　　　　　   73     毫秒  OK
 */
public class Copy {
    public static void main(String[] args)throws IOException {
        long s = System.currentTimeMillis();
        copy_4(new File("c:\\q.exe"), new File("d:\\q.exe"));
        long e = System.currentTimeMillis();
        System.out.println(e-s);
    }
    /*
     * 方法,实现文件复制
     *  4. 字节流缓冲区流读写字节数组
     */
    public static void copy_4(File src,File desc)throws IOException{
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desc));
        int len = 0 ;
        byte[] bytes = new byte[1024];
        while((len = bis.read(bytes))!=-1){
            bos.write(bytes,0,len);
        }
        bos.close();
        bis.close();
    }
    /*
     * 方法,实现文件复制
     *  3. 字节流缓冲区流读写单个字节
     */
    public static void copy_3(File src,File desc)throws IOException{
        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);
        }
        bos.close();
        bis.close();
    }
    
    /*
     * 方法,实现文件复制
     *  2. 字节流读写字节数组
     */
    public static void copy_2(File src,File desc)throws IOException{
        FileInputStream fis = new FileInputStream(src);
        FileOutputStream fos = new FileOutputStream(desc);
        int len = 0 ;
        byte[] bytes = new byte[1024];
        while((len = fis.read(bytes))!=-1){
            fos.write(bytes,0,len);
        }
        fos.close();
        fis.close();
    }
    
    /*
     * 方法,实现文件复制
     *  1. 字节流读写单个字节
     */
    public static void copy_1(File src,File desc)throws IOException{
        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();
    }
}