java - 如何在java控制台(没有UI)中显示下载文件的百分比进度？

Question

我的java代码部分如下。

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来以百分比形式显示下载文件的进度。请帮忙。谢谢。

Answer 1

这是一个简单的“进度条”概念。

基本上，它使用 \b 字符在打印出新进度条之前在先前打印到控制台的字符上退格...

public class TextProgress {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        System.out.println("");
        printProgress(0);
        try {
            for (int index = 0; index < 101; index++) {
                printProgress(index);
                Thread.sleep(125);
            }
        } catch (InterruptedException ex) {
            Logger.getLogger(TextProgress.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void printProgress(int index) {

        int dotCount = (int) (index / 10f);
        StringBuilder sb = new StringBuilder("[");
        for (int count = 0; count < dotCount; count++) {
            sb.append(".");
        }
        for (int count = dotCount; count < 10; count++) {
            sb.append(" ");
        }
        sb.append("]");
        for (int count = 0; count < sb.length(); count++) {
            System.out.print("\b");
        }
        System.out.print(sb.toString());

    }
}

它无法在大多数 IDE 中运行，因为 Java 的文本组件不支持 \b 字符，您必须从终端/控制台运行