How to detect Internet speed ??

I have a pure java program and it will downlod some file from server. When it download files from server, simetime it will take long time if files size is big. I plan to use JProgressBar to show user the progress. But I have a problem to calculate the total time for download. Actually I have below two question:
1) how to detect the Internet speed
2) how to get file size in server side--suppose I have URL for file in server side.

If I can handle above two problems, I can get total download time. Then I can use JProgressBar. Tahnks
gary
garyshiAsked:
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msterjevConnect With a Mentor Commented:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.*;
import java.io.*;
import java.text.DecimalFormat;

public class Downloader extends JFrame implements ActionListener,Runnable
{
     JButton connect;
     JTextArea content;
     JProgressBar progress;
     JTextField address;
     JPanel navigator,progressPanel;
     JLabel estimatedTime;
     Thread thread;
     
     public Downloader()
     {
          super("DOWNLOADER");
          setSize(500,600);
          getContentPane().setLayout(new BorderLayout());
          connect=new JButton("Connect");
          address=new JTextField(30);
          navigator=new JPanel();
          navigator.add(address);
          navigator.add(connect);
          content=new JTextArea(25,50);
          progress=new JProgressBar();
          progress.setForeground(Color.red);
          estimatedTime=new JLabel();
          progressPanel=new JPanel(new GridLayout(2,1));
          progressPanel.add(estimatedTime);
          progressPanel.add(progress);
          getContentPane().add(navigator,BorderLayout.NORTH);
          getContentPane().add(new JScrollPane(content),BorderLayout.CENTER);
          getContentPane().add(progressPanel,BorderLayout.SOUTH);
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          pack();
          connect.addActionListener(this);
          setVisible(true);
     }
     
     public void actionPerformed(ActionEvent e)
     {
          if(e.getSource()==connect)
          {
               if(thread!=null)
               {
                    thread.stop();
                    thread=null;
               }
               progress.setValue(0);
               content.setText("Loading...");
               estimatedTime.setText("");
               thread=new Thread(this);
               thread.start();
          }
     }
     
     public void run()
     {
          DecimalFormat df=new DecimalFormat("#,###.00");
          try
          {
               URL url=new URL(address.getText());
               HttpURLConnection urlConnection=(HttpURLConnection)url.openConnection();
               InputStream in=urlConnection.getInputStream();
               ByteArrayOutputStream baos=new ByteArrayOutputStream();
               BufferedOutputStream bos=new BufferedOutputStream(baos);
               byte[] buffer=new byte[10];
               int contentLength=urlConnection.getContentLength();
               int c,readed;
               readed=0;
               long start=System.currentTimeMillis();
               long end;
               float speed;
               while((c=in.read(buffer,0,10))!=-1)
               {
                    end=System.currentTimeMillis();
                    readed+=c;
                    if((end-start)!=0)
                    {
                         speed=(end-start)/c;
                         start=end;
                         estimatedTime.setText("Estimated time left: "+df.format((contentLength-readed)/(speed*1000.0))+" seconds...");
                    }
                    bos.write(buffer,0,c);
                    progress.setValue((int) (readed*100/contentLength));
                    if(readed==contentLength)
                         break;
               }
               estimatedTime.setText("Finished.");
               in.close();
               urlConnection.disconnect();
               content.setText(new String(baos.toByteArray()));
          }
          catch(Exception e)
          {
               content.setText(e.getClass()+":"+e.getMessage());
          }
     }
     public static void main(String[] args)
     {
          Downloader downloader=new Downloader();
     }
}
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kckchakCommented:
Hi,
For your second question: we can create and URLConnection object and call 'getContentLength()', after 'connect()', which will return the length of the file or content.

Hope this is useful for you.

bye,
kckchak
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msterjevCommented:
You are detecting Internet speed with the information you already have (bytes received). So you must take the start time and calculate the estimated time after each retrieval of chunk of bytes. I would provide you in a short example code.
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msterjevCommented:
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garyshiAuthor Commented:
Hi Msterjev,
Thanks a lot. I got idea to handle this problem. Also thanks all other reponsers.
Gary
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