Java 用逗号显示已下载文件的百分比

我想在应用程序中检查我的下载速度，为此我将从服务器下载1GB的zip文件。我想不出如何用逗号得到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 ");
    }
}

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您可以使用String.format，例如：

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

---

如果我理解正确的话，您想将浮点值四舍五入到逗号后的1位小数吗？如果是这种情况，请尝试以下方法：

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

%.1f

中的

1

是逗号后需要的小数位数，因此，如果您以后决定在逗号后需要2个小数，只需更改此

%.2f

使用：

---

如果需要更灵活的格式，您可以使用。

您需要将

222331664

literal设置为

float

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

若要格式化，请使用：

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

---

我试过了，但总是1,00%-2,00%-3,00%，从来没有1,2%或3,4%

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