OIO、NIO复制文件的比较

1.OIO(BIO)复制文件代码

public static void blockCopyFile(){

        //复制文件39.4G ，共计时间 171s
        InputStream input = null;
        OutputStream output = null;
        File srcFile = new File("C:\\Users\\zxiong\\Downloads\\gradle-7.0_1.zip");
        File destFile = new File("C:\\Users\\zxiong\\Downloads\\gradle-7.0_9.zip");

        try {
            //如果目标文件不存在，则新建
            if (!destFile.exists()) {
                destFile.createNewFile();
            }

            long startTime = System.currentTimeMillis();

            input = new FileInputStream(srcFile);
            output = new FileOutputStream(destFile);
            byte[] buf = new byte[1024*1024*100];
            int bytesRead;
            while ((bytesRead = input.read(buf)) != -1) {
                output.write(buf, 0, bytesRead);
            }
            output.flush();
            long endTime = System.currentTimeMillis();
            log.debug("IO流复制秒数：" + (endTime - startTime)/1000);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            IoUtil.close(input);
            IoUtil.close(output);
        }
    }

2.NIO复制文件代码一

public static void test5() throws Exception{

        //400M/S  149s  39.4G
        FileChannel in4 = new FileInputStream("C:\\Users\\zxiong\\Downloads\\gradle-7.0_1.zip").getChannel();
        FileChannel out4 = new FileOutputStream("C:\\Users\\zxiong\\Downloads\\gradle-7.0_5.zip").getChannel();
        long size = in4.size();
        ByteBuffer bb = ByteBuffer.allocate(1024*1024);
        int length;
        long s = 0;
        long w = 0;
        Instant start = Instant.now();
        NumberFormat numberFormat = NumberFormat.getInstance();
        while((length = in4.read(bb)) != -1){
            s += length;
            String sFormat = numberFormat.format((float) s / (float) size * 100);
            log.info("文件读取进度：{}%", sFormat);
            for (int j = 0; j <= String.valueOf(sFormat).length(); j++) {
                System.out.print("\b");
            }
            bb.flip();
            int len = 0;
            while ((len = out4.write(bb)) != 0){
                w += len;
                String wFormat = numberFormat.format((float) w / (float) size * 100);
                log.info("文件写入进度：{}%", wFormat);
                for (int j = 0; j <= String.valueOf(wFormat).length(); j++) {
                    System.out.print("\b");
                }
            }
            bb.clear();
        }
        in4.close();
        out4.close();
        Instant end = Instant.now();
        long seconds = Duration.between(start, end).getSeconds();
        log.info("文件第五次复制用时(秒):{}",seconds);
    }

3.NIO复制文件代码二

public static void test6() throws Exception{

        //250M/S  161s  39.4G
        FileChannel in4 = new FileInputStream("C:\\Users\\zxiong\\Downloads\\gradle-7.0_1.zip").getChannel();
        FileChannel out4 = new FileOutputStream("C:\\Users\\zxiong\\Downloads\\gradle-7.0_5.zip").getChannel();
        long size = in4.size();
        ByteBuffer bb = ByteBuffer.allocate(1024*1024*512);
        int length;
        long s = 0;
        long w = 0;
        Instant start = Instant.now();
        NumberFormat numberFormat = NumberFormat.getInstance();
        while((length = in4.read(bb)) != -1){
            s += length;
            String sFormat = numberFormat.format((float) s / (float) size * 100);
            log.info("文件读取进度：{}%", sFormat);
            for (int j = 0; j <= String.valueOf(sFormat).length(); j++) {
                System.out.print("\b");
            }
            bb.flip();
            int len = 0;
            while ((len = out4.write(bb)) != 0){
                w += len;
                String wFormat = numberFormat.format((float) w / (float) size * 100);
                log.info("文件写入进度：{}%", wFormat);
                for (int j = 0; j <= String.valueOf(wFormat).length(); j++) {
                    System.out.print("\b");
                }
            }
            bb.clear();
        }
        in4.close();
        out4.close();
        Instant end = Instant.now();
        long seconds = Duration.between(start, end).getSeconds();
        log.info("文件第六次复制用时(秒):{}",seconds);
    }

3.NIO复制文件代码三

 public static void test1() throws Exception{
        //39.4G 140s 
        Instant start = Instant.now();
        FileChannel in1 = new FileInputStream("C:\\Users\\zxiong\\Downloads\\gradle-7.0_2.zip").getChannel();
        FileChannel out1 = new FileOutputStream("C:\\Users\\zxiong\\Downloads\\gradle-7.0_1.zip").getChannel();
        try {
            long size = in1.size();
            log.info("size:{}",size);
            out1.transferFrom(in1, 0, size);
        } catch (IOException e) {
            e.printStackTrace();
        }
        Instant end = Instant.now();
        long seconds = Duration.between(start, end).getSeconds();
        log.info("文件第一次复制时间（秒）：{}",seconds);
    }

4.当前测试环境

interl i7 4核 内存8G

5.总结

在大文件传输上，NIO比BIO传输速率更快一些，以上示例还没有运用到多线程传递数据