如何添加进度条以显示Java中的下载状态？

Question

I am using an external library to download files from Mega but I need a progressbar to display the duration of the download to the user. I have read a lot of progressbar related articles on stackoverflow but the problem is that I don't know what take so long in my code to add a progress bar.

Where and how do I have to add a progressbar to display the download status?

    try {

        URLConnection urlConn = new URL(file_url).openConnection();
        print(file_url);
        is = urlConn.getInputStream();
        while ((read = is.read(buffer)) > 0) {
            cos.write(buffer, 0, read);
        }
    } finally {
        try {
            cos.close();
            if (is != null) {
                is.close();
            }
        } finally {
            if (fos != null) {
                fos.close();
            }
        }
    }
    print("Download finished");
}

Answer 1

You can build a progress bar dialog and preventively show it, and then delegate your costly behind-the-scenes download process to a SwingWorker .

The SwingWorker is a kind of Runnable object (it will be executed behind your main thread) and it is specially conceived to update graphic elements ( publish changes to them) as it does its work.

Have a look at this stackoverflow question:

SwingWorker ProgressBar