Java torrent客户端：tTorrent没有恢复下载

Question

我尝试使用ttorrent Java library开发一个简单的Java BitTorrent client，但是，虽然下载开始并且第一次正常工作，当我停止而不是我尝试恢复它不起作用。

这是代码（有3个类）：

头等舱：

package rar.torrent;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.net.InetAddress;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JTextField;
import javax.swing.filechooser.FileFilter;

import com.turn.ttorrent.client.Client;
import com.turn.ttorrent.client.SharedTorrent;

public class TorrentFrame extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;

    private static final String APRI_BTN = "APRI_BTN";
    private static final String SCEGLI_BTN = "SCEGLI_BTN";
    private static final String PLAY_STOP_BTN = "PLAY_STOP_BTN";

    private static final String PLAY_TXT = "Play";
    private static final String STOP_TXT = "Stop";

    private JTextField torrentFileText = null;
    private JTextField destinazioneText = null;

    private JButton apriButton = null;
    private JButton scegliButton = null;
    private JButton playStopButton = null;

    private JProgressBar jpb = null;

    private JLabel peerLabel = null;

    private JFileChooser torrentJFC = null;
    private JFileChooser directoryJFC = null;

    private SharedTorrent torrent = null;
    private Client client = null;

    private DownloadThread dt = null;

    private File torrentFile = null;
    private File destinazioneFile = null;

    private Thread t = null;

    public TorrentFrame (){
        super("RARTorrent");
        JPanel mainPanel = new JPanel(new GridLayout(5,1));

        JPanel filePanel = new JPanel(new GridLayout(1,3));
        JLabel label = new JLabel("Seleziona file torrent:");
        torrentFileText = new JTextField(20);
        torrentFileText.setText("");
        torrentFileText.setEditable(false);
        apriButton = new JButton("Apri");
        apriButton.setActionCommand(APRI_BTN);
        apriButton.addActionListener(this);
        filePanel.add(label);
        filePanel.add(torrentFileText);
        filePanel.add(apriButton);

        JPanel fileDestPanel = new JPanel(new GridLayout(1,3));
        JLabel labelDest = new JLabel("Seleziona destinazioneText:");
        destinazioneText = new JTextField(20);
        destinazioneText.setText("");
        destinazioneText.setEditable(false);
        scegliButton = new JButton("Scegli");
        scegliButton.setActionCommand(SCEGLI_BTN);
        scegliButton.addActionListener(this);
        fileDestPanel.add(labelDest);
        fileDestPanel.add(destinazioneText);
        fileDestPanel.add(scegliButton);

        playStopButton = new JButton(PLAY_TXT);
        playStopButton.setActionCommand(PLAY_STOP_BTN);
        playStopButton.addActionListener(this);

        jpb = new JProgressBar(0,100);
        jpb.setStringPainted(true);

        peerLabel = new JLabel("Download non in corso");

        torrentJFC = new JFileChooser();
        torrentJFC.setFileSelectionMode(JFileChooser.FILES_ONLY);
        torrentJFC.setAcceptAllFileFilterUsed(false);
        torrentJFC.setFileFilter(new TorrentFileFilter());

        directoryJFC = new JFileChooser();
        directoryJFC.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);

        mainPanel.add(filePanel);
        mainPanel.add(fileDestPanel);
        mainPanel.add(playStopButton);
        mainPanel.add(jpb); 
        mainPanel.add(peerLabel);

        this.add(mainPanel);

        this.pack();
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }

    private class TorrentFileFilter extends FileFilter{

        @Override
        public boolean accept(File f) {
            String ext = null;
            String s = f.getName();
            int i = s.lastIndexOf('.');

            if (i > 0 &&  i < s.length() - 1) {
                ext = s.substring(i+1).toLowerCase();
            }

            if (ext != null && ext.equals("torrent"))
                return true;

            return false;
        }

        @Override
        public String getDescription() {
            return "Torrent files";
        }

    }

    @Override
    public void actionPerformed(ActionEvent arg0) {
        String ev = arg0.getActionCommand();

        if(ev.equalsIgnoreCase(APRI_BTN)){          
            int returnVal = torrentJFC.showOpenDialog(this);

            if (returnVal == JFileChooser.APPROVE_OPTION) {
                torrentFile = torrentJFC.getSelectedFile();
                torrentFileText.setText(torrentFile.getName());
            } else {
                System.out.println("Chiuso 'Apri file'");
            }           
        }

        if(ev.equalsIgnoreCase(PLAY_STOP_BTN)){
            if (playStopButton.getText().equalsIgnoreCase(STOP_TXT)){
                client.stop();
                dt.stop();
                client = null;
                t = null;
                dt = null;
                torrent = null;
                playStopButton.setText(PLAY_TXT);
                return;
            }

            if (playStopButton.getText().equalsIgnoreCase(PLAY_TXT) && !torrentFileText.getText().equalsIgnoreCase("") && !destinazioneText.getText().equalsIgnoreCase("")){
                try {
                    torrent = SharedTorrent.fromFile(torrentFile, destinazioneFile);
                    client = new Client(InetAddress.getLocalHost(),torrent);
                    client.setMaxDownloadRate(1000.0);
                    client.setMaxUploadRate(50.0);
                    client.download();

                    jpb.setValue(0);
                    peerLabel.setText("Non in download");
                    dt = new DownloadThread(jpb,peerLabel,torrent);
                    t = new Thread (dt);
                    t.start();

                    playStopButton.setText(STOP_TXT);
                } catch (IOException e) {
                    JOptionPane.showMessageDialog(this, e.getMessage());
                }
            }           
        }

        if(ev.equalsIgnoreCase(SCEGLI_BTN)){
            int returnVal = directoryJFC.showSaveDialog(this);

            if (returnVal == JFileChooser.APPROVE_OPTION) {
                destinazioneFile = directoryJFC.getSelectedFile();
                destinazioneText.setText(destinazioneFile.getName());
            } else {
                System.out.println("Chiuso 'Scegli'");
            }
        }

    }

}

第二课：

package rar.torrent;

import java.text.SimpleDateFormat;
import java.util.Calendar;

import javax.swing.JLabel;
import javax.swing.JProgressBar;

import com.turn.ttorrent.client.SharedTorrent;

public class DownloadThread implements Runnable {
    private JProgressBar jpb = null;
    private SharedTorrent torrent = null;
    private JLabel peerLabel = null;

    private int completedPieces = 0;
    private int pieceCount = 0;
    private int availablePieces = 0;
    private int requestedPieces = 0;

    private String peerLabelText = "";

    private boolean stop = false;

    public DownloadThread(JProgressBar jpb, JLabel peerLabel, SharedTorrent torrent){
        super();
        this.jpb = jpb;
        this.torrent = torrent;
        this.peerLabel = peerLabel;
    }

    @Override
    public void run() {
        while (!torrent.isComplete() && !stop){
            Calendar cal = Calendar.getInstance();
            SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");

            float perc = torrent.getCompletion();
            int percInt = (int) perc;
            int jpbValue = jpb.getValue();
            if (percInt > jpbValue)
                jpb.setValue(percInt);

            //TODO Sistemare il bug della "," nella stringa sostituendola con il "."
            String stringToFloat = jpb.getString().substring(0, jpb.getString().length() -1);
            int comaChar = stringToFloat.lastIndexOf(",");
            char [] transformString = stringToFloat.toCharArray();
            if (comaChar > 0)
                transformString [comaChar] = '.';
            stringToFloat = new String(transformString);

            if (perc > Float.parseFloat(stringToFloat))
                jpb.setString(String.format("%.2f", perc) + "%");

            completedPieces = torrent.getCompletedPieces().cardinality();
            pieceCount = torrent.getPieceCount();
            availablePieces = torrent.getAvailablePieces().cardinality();
            requestedPieces = torrent.getRequestedPieces().cardinality();

            if (isPeerLabelTextModified(cal,sdf)){
                peerLabelText = completedPieces + "/" + pieceCount + " pieces [" + availablePieces + "/" + requestedPieces + "] \n" + sdf.format(cal.getTime());
                peerLabel.setText(peerLabelText);
            }

        }
    }

    private boolean isPeerLabelTextModified (Calendar cal, SimpleDateFormat sdf){
        String test = completedPieces + "/" + pieceCount + " pieces [" + availablePieces + "/" + requestedPieces + "]  " + sdf.format(cal.getTime());
        return !peerLabelText.equalsIgnoreCase(test);
    }

    public void stop(){
        this.stop = true;
    }
}

第三课：

package rar.torrent;

import javax.swing.*;

public class RARTorrent{    

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){

            @Override
            public void run() {
                new TorrentFrame();
            }});
    }
}

非常感谢！