源码

java – JProgressBar不会更新


我正在尝试从这个问题的投票答案中找到的代码:Download file using java apache commons?

这是一个下载应用程序,看一看,(我对JFrames和ActionEvents不是很熟悉)

Download.java

package main;

public class Download extends JFrame implements Runnable{

    public static int total;
    public static int done;

    private static class ProgressListener implements ActionListener{

        @Override
        public void actionPerformed(ActionEvent e) {

            done = (int)((DownloadCountingOutputStream) e.getSource()).getByteCount();
            jbar.repaint();
            DownloadCountingOutputStream.parent.draw((int)((DownloadCountingOutputStream) e.getSource()).getByteCount());//redraw
            DownloadCountingOutputStream.parent.repaint();
        }
    }

    public static JProgressBar jbar = new JProgressBar(); 



    public void draw(int downloaded){System.out.println("downloaded: "+downloaded+ " Total: "+total);

        if (downloaded== 0){

        Container cont = new Container();       
        setDefaultCloseOperation(3);
        setSize(600, 450);
        setResizable(false);
        setVisible(true);

        cont.add(jbar);     
        jbar.setBounds(40, 50, 500, 50);                
        jbar.setMaximum(total);//The total value of bytes to download
        //jbar.setValue(50);
        add(cont);

        jbar.setVisible(true);  
        }

        jbar.setValue(downloaded);      
            //This should update the value of the progress Bar
    }

    public void run() {


        URL dl = null;
        File fl = null;
        OutputStream os = null;
        InputStream is = null;
        ProgressListener progressListener = new ProgressListener();

        draw(done);

        try {
            fl = new File(System.getProperty("user.home").replace("//", "/") + "/Desktop/afile.rar");
            dl = new URL("https://dl.dropbox.com/u/48076798/afile.rar");
            os = new FileOutputStream(fl);
            is = dl.openStream();

            total = Integer.parseInt(dl.openConnection().getHeaderField("Content-Length"));

            String total = dl.openConnection().getHeaderField("Content-Length");

            DownloadCountingOutputStream dcount = new DownloadCountingOutputStream(os);
            dcount.setListener(progressListener);
            dcount.setParent(this);

            IOUtils.copy(is, dcount);

        } catch (Exception e) {
            System.out.println(e);
        } finally {
            if (os != null) { 
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                } 
            }
            if (is != null) { 
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                } 
            }
        }
    }

}

DownloadCountingOutputStream.java

package main;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.OutputStream;

import org.apache.commons.io.output.CountingOutputStream;

public class DownloadCountingOutputStream extends CountingOutputStream {

    private ActionListener listener = null;
    public static Download parent;

    public DownloadCountingOutputStream(OutputStream out) {
        super(out);
    }

    public void setListener(ActionListener listener) {
        this.listener = listener;
    }

    public void setParent(Download o){

        parent = o;
    }

    @Override
    protected void afterWrite(int n) throws IOException {
        super.afterWrite(n);
        if (listener != null) {
            listener.actionPerformed(new ActionEvent(this, 0, null));
        }
    }

}
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本文由 投稿者 创作,文章地址:https://blog.isoyu.com/archives/java-jprogressbarbuhuigengxin.html
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