...
                int max = inStream.available();
                nomeBarra.setMaximum(max); // numero di byte totali
                nomeBarra.setValue(0); // numero di byte letti
                while (inStream.available() > 0)
                    {
                    outStream.write(inStream.read());
                    nomeBarra.setValue(max - inStream.available()); // totali - ancora_da_leggere = quelli letti
                                                                    // volendo puoi fare in percentuale dividento per 100
                                                                    // ovviamente troncando o arrotondando.
                    }
                ...

//~--- JDK imports ------------------------------------------------------------

import java.awt.Dimension;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.File;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;

public class UploadApplet extends javax.swing.JApplet {

    private File[]      fileScelti;
    private JButton     jBtbUpload;
    private JList       jList1;
    private JScrollPane jScrollPane1;
    private JButton     jUploadBtb;

    public UploadApplet() {

        super();
        initGUI();
    }

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {

            public void run() {

                JFrame       frame = new JFrame();
                UploadApplet inst  = new UploadApplet();

                frame.getContentPane().add(inst);
                ((JComponent) frame.getContentPane()).setPreferredSize(inst.getSize());
                frame.pack();
                frame.setVisible(true);
            }

        });
    }

    private void initGUI() {

        try
            {
            setSize(new Dimension(400, 300));
            getContentPane().setLayout(null);

            {
                jScrollPane1 = new JScrollPane();
                getContentPane().add(jScrollPane1);
                jScrollPane1.setBounds(27, 22, 273, 129);
                {}
            }

            {
                jUploadBtb = new JButton();
                getContentPane().add(jUploadBtb);
                jUploadBtb.setText("Apri");
                jUploadBtb.setBounds(319, 22, 46, 26);
                jUploadBtb.setFont(new java.awt.Font("Tahoma", 0, 8));
                jUploadBtb.addMouseListener(new MouseAdapter() {

                    public void mouseClicked(MouseEvent evt) {
                        jUploadBtbMouseClicked(evt);
                    }

                });
            }

            {
                jBtbUpload = new JButton();
                getContentPane().add(jBtbUpload);
                jBtbUpload.setText("Upload");
                jBtbUpload.setBounds(142, 194, 91, 34);
                jBtbUpload.addMouseListener(new MouseAdapter() {

                    public void mouseClicked(MouseEvent evt) {
                        jBtbUploadMouseClicked(evt);
                    }

                });
            }
            }
        catch (Exception e)
            {
            e.printStackTrace();
            }
    }

    private void jUploadBtbMouseClicked(MouseEvent evt) {

        JFileChooser chooser = new JFileChooser();

        chooser.setMultiSelectionEnabled(true);
        chooser.showOpenDialog(this);

        File[] files = chooser.getSelectedFiles();

        this.fileScelti = files;

        String elementi[] = new String[files.length];

        for (int i = 0; i < files.length; i++) {

            elementi[i] = files[i].getName();
            System.out.println(files[i].getPath());
        }

        jList1 = new JList(elementi);
        jScrollPane1.setViewportView(jList1);
        jList1.setPreferredSize(new java.awt.Dimension(486, 262));
    }

    private void jBtbUploadMouseClicked(MouseEvent evt) {

        String     url = "http://localhost:80/Massimo/ControllerFiles";
        HtppUpload up  = new HtppUpload();

        up.setURL(url);
        up.setTargetFile(fileScelti);
        up.UploadFile();
    }
}

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.methods.multipart.FilePart;
import org.apache.commons.httpclient.methods.multipart.MultipartRequestEntity;
import org.apache.commons.httpclient.methods.multipart.Part;
import org.apache.commons.httpclient.params.HttpMethodParams;

//~--- JDK imports ------------------------------------------------------------

import java.io.File;

public class HtppUpload {

    private String URL;
    private File[]   targetFile;



	public void UploadFile() {
for (int i=0; i<targetFile.length; i++)
{
        PostMethod filePost = new PostMethod(URL);

        filePost.getParams().setBooleanParameter(HttpMethodParams.USE_EXPECT_CONTINUE, false);

        try
            {
            Part[] parts = { new FilePart(targetFile[i].getName(), targetFile[i]) };

            filePost.setRequestEntity(new MultipartRequestEntity(parts, filePost.getParams()));

            HttpClient client = new HttpClient();

            client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);

            int status = client.executeMethod(filePost);

            if (status == HttpStatus.SC_OK) {
                System.out.println("Upload complete, response= " + filePost.getResponseBodyAsString());
            } else {
                System.out.println("Upload failed, response=" + HttpStatus.getStatusText(status));
            }
            }
        catch (Exception ex)
            {
            System.out.println("ERROR: " + ex.getClass().getName() + " " + ex.getMessage());
            ex.printStackTrace();
            }
        finally
            {
            filePost.releaseConnection();
            }
        }
    }

    public String getURL() {
        return URL;
    }

    public void setURL(String url) {
        URL = url;
    }

    public File[] getTargetFile() {
		return targetFile;
	}

	public void setTargetFile(File[] targetFile) {
		this.targetFile = targetFile;
	}
}