下載器-http 進度條 文件讀寫

final JButton button = new JButton("下載");  
button.addActionListener(new ActionListener() 
{ 
    public void actionPerformed(ActionEvent e) 
    { 
        new Thread() 
        { 
            @Override 
            public void run() 
            { 
                button.setEnabled(false);//設置按鈕在下載過程中不可操作 
                FileOutputStream fos = null; 
                try 
                { 
                    URL url = new URL(txtFilefjavaindexhtml.getText());//建立HTTP連接 
                    URLConnection conn = url.openConnection();//創建連接對象 
                     
                    int fileSize = conn.getContentLength();//用getContentLength()得到連接對象的文件大小 
                     
                    InputStream is = conn.getInputStream(); 
                    byte[] buffer = new byte[1024]; 
                    int length = 0; 
                     
                    fos = new FileOutputStream(txtFilefjavaindexhtml_1.getText()); 
                             
                    double downSize = 0; 
                    while (-1 != (length = is.read(buffer))) 
                    { 
                        downSize += length; 
                        double percent = downSize * 100 / fileSize;//計算下載百分比 
                        fos.write(buffer, 0, length); 
                        progressBar.setValue((int) percent);//設置進度條變化 
                    } 
                } 
                catch (MalformedURLException e1) 
                { 
                    e1.printStackTrace(); 
                } 
                catch (IOException e1) 
                { 
                    e1.printStackTrace(); 
                } 
                finally//輸出流要記得在fanally關掉 
                { 
                    button.setEnabled(true);//在finally中恢復按鈕可操作 
                    if (null != fos) 
                    { 
                        try 
                        { 
                            fos.close(); 
                        } 
                        catch (IOException e1) 
                        { 
                            e1.printStackTrace(); 
                        } 
                    } 
                } 
            } 
        }.start(); 
         
    } 
}); 
button.setFont(new Font("宋體", Font.PLAIN, 24)); 
button.setBounds(10, 164, 97, 37); 
frame.getContentPane().add(button); 
 
progressBar = new JProgressBar(); 
progressBar.setBounds(152, 164, 272, 37); 
frame.getContentPane().add(progressBar);//進度條按鈕