用逗号显示下载文件的百分比

Question

我想检查我在应用程序中的下载速度，为此我将从服务器下载一个 1GB 的 zip 文件。我无法弄清楚如何用逗号获得 12,4% 或 45,8% 这样的数字。确切的文件大小是 222331664 字节

import java.net.*;
import java.io.*;

public class SpeedTest
{
    private static Logger log;
    private static URL fileToDownload;

    public static void main(String argc[]) throws Exception {
        log = new Logger("SpeedTest");

        // http://kernel.ubuntu.com/~kernel-ppa/mainline/v2.6.15/linux-headers-2.6.15-020615_2.6.15-020615_all.deb
        fileToDownload = new URL("http://www.specialservice.ml/1GB.zip");

        log.logToLogger("Lade " + fileToDownload);

        long totalDownload = 0; // total bytes downloaded
        final int BUFFER_SIZE = 1024; // size of the buffer
        byte[] data = new byte[BUFFER_SIZE]; // buffer
        BufferedInputStream in = new BufferedInputStream(fileToDownload.openStream());
        int dataRead = 0; // data read in each try
        long startTime = System.nanoTime(); // starting time of download

        while ((dataRead = in.read(data, 0, 1024)) > 0) {
            totalDownload += dataRead; // adding data downloaded to total data
            float tempPercentage = (totalDownload * 100) / 222331664;
            log.logToLogger("lade " + dataRead + " Bytes -> " + String.format("%.2f", tempPercentage) + "% geladen"); 
        }

        /* download rate in bytes per second */
        float bytesPerSec = totalDownload / ((System.nanoTime() - startTime) / 1000000000);
        log.logToLogger(bytesPerSec + " Bps");

        /* download rate in kilobytes per second */
        float kbPerSec = bytesPerSec / (1024);
        log.logToLogger(kbPerSec + " KBps ");

        /* download rate in megabytes per second */
        float mbPerSec = kbPerSec / (1024);
        log.logToLogger(mbPerSec + " MBps ");
    }
}

Answer 1

您可以使用String.format，例如：

String.format("%.2f", tempPercentage);

Answer 2

如果我没理解错的话，您想将逗号后的浮点数四舍五入为小数点后一位？如果是这样，试试这个：

float tempPercentage = (totalDownload * 100) / 222331664;
String roundedPercentage = String.format("%.1f, tempPercentage);
log.logToLogger("lade " + dataRead + " Bytes -> " + roundedPercentage + "% geladen");

%.1f 中的 1 是您希望在逗号后保留多少位小数，因此如果您稍后决定在逗号后保留 2 位小数，只需更改此 %.2f。

Answer 3

使用DecimalFormat:

DecimalFormat df = new DecimalFormat();
DecimalFormatSymbols symbols = new DecimalFormatSymbols();
symbols.setDecimalSeparator(',');
df.setDecimalFormatSymbols(symbols);
     log.logToLogger("lade " + dataRead + " Bytes -> " + ´df.format(tempPercentage) + "% geladen");

Answer 4

如果您需要更灵活的格式，可以使用DecimalFormat。

Answer 5

您需要将 222331664 字面量设为 float

float tempPercentage = (totalDownload * 100) / 222331664f;

并使用以下格式对其进行格式化：

String.format("%.1f", tempPercentage).replace(".", ",");

用逗号显示下载文件的百分比

Display the percentage of an downloaded file with comma

java

file

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