Question

我用Opera浏览器和Java代码尝试过相同的文件。

Opera浏览器的速度接近2 MB / s，但Java代码的速度不超过400 KB / s。我的代码出了什么问题？

我想我在使用BufferedReader阅读时做错了，但我不知道它为什么会发生，我该如何解决。

PS：我只进行速度测试，而不是运行文件。我知道它是一个二进制文件，这会对速度有什么不同吗？

            StringBuilder builder = new StringBuilder();
            HttpURLConnection uri = (HttpURLConnection) new URL("http://speedtest.tele2.net/3MB.zip").openConnection();
            uri.setRequestMethod("GET");
            uri.setConnectTimeout(5000);
            InputStream ent = uri.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(ent, "iso-8859-1"), 8);
            while ((line = reader.readLine()) != null) {
                builder.append(line + "\n");
            }

Answer 1

我会使用二进制文件下载二进制文件，当我运行时我得到

SUM()

打印

public class DownloadMain {
    public static void main(String[] args) throws IOException {
        HttpURLConnection uri = (HttpURLConnection) new URL("http://speedtest.tele2.net/3MB.zip").openConnection();
        uri.setRequestMethod("GET");
        uri.setConnectTimeout(5000);
        InputStream ent = uri.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] bytes = new byte[8192];
        long start = System.currentTimeMillis();
        for (int len; (len = ent.read(bytes)) > 0; )
            baos.write(bytes, 0, len);
        long time = System.currentTimeMillis() - start;
        System.out.printf("Took %.3f seconds to read %.3f MB of data%n",
                time / 1e3, baos.toByteArray().length / 1e6);
    }
}

几乎是6 MB / s

如果忽略文件为二进制文件的事实，仅用于性能比较。

Took 0.541 seconds to read 3.146 MB of data

打印

public class DownloadMain {
    public static void main(String[] args) throws IOException {
        HttpURLConnection uri = (HttpURLConnection) new URL("http://speedtest.tele2.net/3MB.zip").openConnection();
        uri.setRequestMethod("GET");
        uri.setConnectTimeout(5000);
        InputStream ent =uri.getInputStream();
        Reader reader = new InputStreamReader(ent, StandardCharsets.ISO_8859_1);
        StringWriter sw = new StringWriter();
        char[] chars = new char[8192];
        long start = System.currentTimeMillis();
        for (int len; (len = reader.read(chars)) > 0; )
            sw.write(chars, 0, len);
        long time = System.currentTimeMillis() - start;
        System.out.printf("Took %.3f seconds to read %.3f MB of data%n",
                time / 1e3, sw.toString().length() / 1e6);
    }
}

所以它可能会稍慢，或者只是随机变化。

相比之下，使用StringBuilder并一次读取一行可能会更慢，但不会显着

Took 0.548 seconds to read 3.146 MB of data

下载文件太慢了

1 个答案: