CopyFile.java簡單的展示如何使用JProgressBar顯示檔案複製進度

/* @description: 簡單的展示如何使用JProgressBar顯示檔案複製進度
 * @source: Introduction to Java Programming Sixth Edition,Y.DANIEL LIANG
 * @chapter: MultiThreading, p.832
 **/

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.io.*;

public class CopyFile extends JFrame{
    private JProgressBar progressBar = new JProgressBar();
    private JButton btnCopy = new JButton("Copy");
    private JTextField txtFrom = new JTextField();
    private JTextField txtTo = new JTextField();
    
    public CopyFile() {
        //檔案來源
        JPanel panelFrom = new JPanel();
        panelFrom.setLayout(new BorderLayout());
        panelFrom.setBorder(new TitledBorder("From"));
        panelFrom.add(txtFrom, BorderLayout.CENTER);
        //檔案目的
        JPanel panelTo = new JPanel();
        panelTo.setLayout(new BorderLayout());
        panelTo.setBorder(new TitledBorder("To"));
        panelTo.add(txtTo, BorderLayout.CENTER);
        //放置容器
        JPanel panelContainer = new JPanel();
        panelContainer.setLayout(new GridLayout(2,1));
        panelContainer.add(panelFrom);
        panelContainer.add(panelTo);
        //複製按鈕
        JPanel panelCopy = new JPanel();
        panelCopy.add(btnCopy);
        
            
        this.add(progressBar , BorderLayout.NORTH);
        this.add(panelContainer , BorderLayout.CENTER);
        this.add(panelCopy , BorderLayout.SOUTH);
        
        //設進度表百分比
        progressBar.setStringPainted(true);
        
        btnCopy.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                        btnCopy.setEnabled(false);
                        new Thread(new CopyFileTask()).start();
                        
                    }
            });
        
        
    }
    
    public static void main(String args[]) {
        CopyFile frame = new CopyFile();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Copy File");
        frame.setSize(400,180);
        frame.setLocation(300,180);
        frame.setResizable(false);
        frame.setVisible(true);
    }
    
    //inner class
    class CopyFileTask implements Runnable {
        private int currentValue;
        public void run() {
            //負責輸入Stream
            BufferedInputStream in = null;
            //負責輸出Stream
            BufferedOutputStream out = null;
            try {
                File inFile = new File(txtFrom.getText().trim());
                in = new BufferedInputStream(new FileInputStream(inFile));
                
                File outFile = new File(txtTo.getText().trim());
                out = new BufferedOutputStream(new FileOutputStream(outFile));
                //來源檔案總共讀取多少Bytes
                long totalBytes = in.available();
                //設置初始值與最大值
                progressBar.setValue(0);
                progressBar.setMaximum(100);
                //複製來源檔案到目的檔案
                int r ;
                long byteRead = 0;
                byte[] b = new byte[1024];
                while((r = in.read(b,0,b.length)) != -1) {
                    out.write(b, 0 , r);
                    //累加讀取了多少Bytes,並且顯示在JProgressBar
                    byteRead += r;
                    currentValue = (int) (byteRead * 100 / totalBytes);
                    progressBar.setValue(currentValue);
                }

            }catch(FileNotFoundException fnfE) {
                fnfE.printStackTrace();
            }catch(IOException ioE) {
                ioE.printStackTrace();
            }finally {
                btnCopy.setEnabled(true);
                try {
                    if( in != null) in.close();
                    if(out != null) out.close();
                    
                }catch(Exception ex) {}
            }
        }
    }
    
}