如何在java控制台(没有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

如果你对这样的输出感到满意

If you are satisfied with output like

正在下载文件 ... 10% ... 20% ... 38% ...

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

不断追加到行中，您可以只print 而不是println.如果你想做一些有限的事情，比如只更新几个字符，你可以打印退格字符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退格来擦除附加的文本.

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

比这更复杂的事情，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/

我从来没有用过这个，所以我不能保证它.如果不正确，快速 Google 会显示许多替代方案.

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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