如何在 Java 控制台(无 UI)中显示下载文件的百分比进度? [英] How to show percentage progress of a downloading file in java console(without UI)?

问题描述

我的部分java代码如下.

My part of java code is below.

while (status == DOWNLOADING) {
    /* Size buffer according to how much of the
       file is left to download. */
            byte buffer[];
            if (size - downloaded > MAX_BUFFER_SIZE) {
                buffer = new byte[MAX_BUFFER_SIZE];
            } else {
                buffer = new byte[size - downloaded];
            }

            // Read from server into buffer.
            int read = stream.read(buffer);
            if (read == -1){
                System.out.println("File was downloaded");
                break;
            }

            // Write buffer to file.
            file.write(buffer, 0, read);
            downloaded += read;

        }

  /* Change status to complete if this point was
     reached because downloading has finished. */
        if (status == DOWNLOADING) {
            status = COMPLETE;

        }

我想通过更新控制台中的进度行以百分比形式显示下载文件的进度.请帮忙.谢谢.

I want to show the progress of the downloading file as percentage by updating the progress line in console. Please help. Thanks.

推荐答案

如果你对输出满意的话

正在下载文件 ... 10% ... 20% ... 38% ...

Downloading file ... 10% ... 20% ... 38% ...

不断追加到该行，你可以只 print 而不是 println.如果您想做一些有限的事情，比如只更新几个字符，您可以打印退格字符以擦除然后重新打印百分比，例如:

that keeps appending to the line, you can just print instead of println. If you want to do something limited like just update a few characters in place, you can print the backspace character to erase then re-print the percent, for example:

System.out.print("index at: X");
int lastSize = 1;
for (int i = 0; i < 100; i++) {
  for (int j = 0; j < lastSize; j++) {
    System.out.print("");
  }
  String is = String.toString(i);
  System.out.print(is);
  lastSize = is.length();
}

注意代码如何跟踪打印了多少个字符，因此它知道要打印多少个退格键来擦除附加的文本.

Note how the code tracks how many characters were printed, so it knows how many backspaces to print to erase the appended text.

比这更复杂的是，您需要某种控制台或终端控制 SDK.ncurses 是 Unix 标准，看起来有一个 Java 端口:

Something more complex than that, you need some sort of console or terminal control SDK. ncurses is the Unix standard, and it looks like there's a Java port:

http://sourceforge.net/projects/javacurses/

我从来没有使用过这个，所以我不能保证它.如果它不正确，快速谷歌显示了许多替代方案.

I have never used this one so I can't vouch for it. If it's not right, a quick Google showed many alternatives.

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