Java文件快速copy复制

谁践踏了优雅 2022-12-31 12:19 148阅读 0赞

最近学习netty的时候发现nio包下有个FileChannel类，经过了解这个类作用是个专门负责传输文件的通道，支持多线程，而且经过反复多次测试FileChannel复制文件的速度比BufferedInputStream/BufferedOutputStream复制文件的速度快了近三分之一。在复制大文件的时候更加体现出FileChannel的速度优势。而且FileChannel是多并发线程安全的。代码也比较简洁

代码贴下

> 关于这种io流关闭方式不清楚的同学请看我这篇文章：[https://laoniu.blog.csdn.net/article/details/111896446][https_laoniu.blog.csdn.net_article_details_111896446]

# 测试对比 #

复制目标文件:

![20201229171511120.png][]

4.76GB

代码

package com.niu.nio;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.nio.channels.FileChannel;
    
    /**
     * @description:
     * @author: nxq email: niuxiangqian163@163.com
     * @createDate: 2020/12/28 5:48 下午
     * @updateUser: nxq email: niuxiangqian163@163.com
     * @updateDate: 2020/12/28 5:48 下午
     * @updateRemark:
     * @version: 1.0
     **/
    public class Main {
        public static void main(String[] args) {
            long start = System.currentTimeMillis();
            File src = new File("/Users/laoniu/Downloads/installer/cn_windows_10_business_edition_version_1809_updated_sept_2018_x64_dvd_fc5542c0.iso"); //文件4.76GB
         quickCopy(src,new File("/Users/laoniu/test/a.iso"));
             long end = System.currentTimeMillis();
            System.out.println("FileChannel复制:"+(end - start));
    
             start = System.currentTimeMillis();
            copy(src,new File("/Users/laoniu/test/b.iso"));
             end = System.currentTimeMillis();
            System.out.println("普通复制:"+(end - start));
    
    
        }
        /**
         * 快速copy
         * @author nxq
         * @param src: 源文件
         * @param target: 目标文件
         * @return void
         */
        public static void quickCopy(File src, File target){
            try(FileInputStream inputStream = new FileInputStream(src);
                FileOutputStream outputStream = new FileOutputStream(target);
                FileChannel inputChannel = inputStream.getChannel(); // 得到源文件文件通道
                FileChannel outputChannel = outputStream.getChannel()// 得到目标文件通道
            ) {
                //将源文件数据通达连通到目标文件通道进行传输
                inputChannel.transferTo(0,inputChannel.size(),outputChannel);
            }catch (Exception e){
                e.printStackTrace();
            }
        }
        /**
         * 普通copy
         * @author nxq
         * @param src:
         * @param target:
         * @return void
         */
        public static void copy(File src, File target){
            try(FileInputStream inputStream = new FileInputStream(src);
                FileOutputStream outputStream = new FileOutputStream(target);
            ) {
                byte[] data = new byte[1024*1024]; //加大每次读取的数据多少
                int len;
                while ((len = inputStream.read(data))!=-1){
                    outputStream.write(data,0,len);
                }
    
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    
    }

加大每次读取的数据到1024\*1024，否则更慢

结果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70][]

[https_laoniu.blog.csdn.net_article_details_111896446]: https://laoniu.blog.csdn.net/article/details/111896446
[20201229171511120.png]: /images/20221120/f89aca4f9e0141b9aa08c808a7b68c1a.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMzg5MzU0_size_16_color_FFFFFF_t_70]: /images/20221120/1a54c05704d44270900fcec0dd780d56.png