java – 为什么我的流复制过程的性能稳定下降

发布时间：2020-12-15 04:50:16 所属栏目：Java 来源：网络整理

导读：在复制大文件期间,此代码的工作速度越来越慢.难道我做错了什么？ InputStream ms2 = new BufferedInputStream(new FileInputStream("/home/fedd/Videos/homevid.mp4")); OutputStream fos2 = new BufferedOutputStream(new FileOutputStream("testfile2.mp4"

在复制大文件期间,此代码的工作速度越来越慢.难道我做错了什么？

InputStream ms2 = new BufferedInputStream(new FileInputStream("/home/fedd/Videos/homevid.mp4"));
    OutputStream fos2 = new BufferedOutputStream(new FileOutputStream("testfile2.mp4",true));

    try {
        int byt;
        int i = 0;
        long time = System.currentTimeMillis();
        while ((byt = ms2.read()) != -1) {
            fos2.write(byt);
            i++;
            if (i > 100000) {
                i = 0;
                long took = System.currentTimeMillis() - time;
                System.out.println("100000 bytes took " + took + " milliseconds which means " + (100000000 / took) + " bytes per second");
            }
        }
        fos2.close();
        ms2.close();
    } catch (Exception e) {
        throw new RuntimeException(e);
    }

我的Java是：

openjdk 10.0.2 2018-07-17 OpenJDK Runtime Environment (build
10.0.2+13-Ubuntu-1ubuntu0.18.04.4)

OpenJDK 64-Bit Server VM (build 10.0.2+13-Ubuntu-1ubuntu0.18.04.4,
mixed mode)

解决方法

每次比较后,您需要重置基准’时间’.试试这个：

if (i > 100000) {
    i = 0;
    long took = System.currentTimeMillis() - time;
    time = System.currentTimeMillis();
    System.out.println("100000 bytes took " + took + " milliseconds which means " + (100000000 / took) + " bytes per second");
}

（编辑：李大同）

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