使用 Java 复制文件时的进度条

我敢肯定这个问题以前问过，但是我找到的答案都不能很好地与我现有的代码配合。我发布这个问题是为了以防万一有办法做到这一点，而无需完全重做我迄今为止所拥有的内容。

这个想法是在将文件和目录从一个驱动器复制到另一个驱动器时显示一个非常基本的进度条。我有一个名为 BasicCopy 的类，它旨在将“图片”、“文档”、“视频”和“音乐”文件夹（Windows 计算机上的标准）的内容复制到第二个驱动器上的备份目录中的同名文件夹中。这是到目前为止的类：

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.commons.io.FileUtils;

public class BasicCopy {

    String username = "";
    String mainDrive = "";
    String backupDrive = "";
    String backupDir = "";
    String[] directories;

    public BasicCopy(String inDrive, String outDrive, String username){
        mainDrive = inDrive;
        backupDrive = outDrive;
        this.username = username;

        createBackupDirectory();
        copyDirectories();

        close();
    }

    //Create backup directory
    public void createBackupDirectory(){
        Date date = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("MM-dd-yyyy_HMMSS");
        String timestamp = sdf.format(date);
        backupDir = backupDrive + ":\\" + "Backup " + timestamp;
        File backupDirectory = new File(backupDir);
        backupDirectory.mkdir();
    }

    public void copyDirectories(){
        //Main directories
        String pics = mainDrive + ":\\Users\\" + username + "\\Pictures";
        String docs = mainDrive + ":\\Users\\" + username + "\\Documents";
        String vids = mainDrive + ":\\Users\\" + username + "\\Videos";
        String musc = mainDrive + ":\\Users\\" + username + "\\Music";
        //Backup directories
        String bkPics = backupDir + "\\Pictures";
        String bkDocs = backupDir + "\\Documents";
        String bkVids = backupDir + "\\Documents";
        String bkMusc = backupDir + "\\Pictures";

        String[] directories = {pics, docs, vids, musc};
        String[] bkDirectories = {bkPics, bkDocs, bkVids, bkMusc};

        //Loop through directories and copy files
        for (int i = 0; i < directories.length; i++){
            File src = new File(directories[i]);
            File dest = new File(bkDirectories[i]);
            try{
                FileUtils.copyDirectory(src, dest);
            } catch (IOException e){
                e.printStackTrace();
            }
        }
    }

    /* Close current process */
    public void close(){
        System.exit(0);
    }
}

我在前面的类中有一个测量目录总大小的方法，因此，如有必要，我可以将其传递给该类。但是，我目前只遍历这四个目录，所以我预计我无法以高于每次价格变动 25% 的分辨率递增进度条。我想知道是否有一种方法可以更改它，以便我可以包含一个进度条来监视它，并使其更准确一些？此外，我不确定是否应该在不同的线程中询问这个问题，但是这种文件复制方法需要很长时间。复制500MB的文件需要几个小时，我想知道是否有办法加快速度？不过，这部分不是优先事项。现在我主要对添加进度条感兴趣。干杯！

编辑：

经过一些摆弄，我意识到我可能会使用与此类似的代码（这个确切的代码可能会也可能不会起作用 - 我只是快速记下它，所以我不会忘记它，它仍然没有经过测试）。这将允许我更新复制的每个文件的进度条。

for (int i = 0; i < directories.length; i++){
    File dir = new File(directories[i]);
    File dest = new File(bkDirectories[i]);
    for(File file: dir.listFiles()){
        try{
            FileUtils.copyDirectory(file, dest);
            //update progress bar here
        } catch (IOException e){
            e.printStackTrace();
        }
    }
}

编辑#2：

我在代码上做了更多的工作，我相信我已经弄清楚了大部分。现在的问题是关于SwingWorker的，我相信我需要它才能在后台运行长期方法。否则，GUI将变得无响应（Java文档中有很多关于此的文档）。但是，这是我陷入困境的地方。我以前只使用过一次SwingWorker，主要是复制的代码。我想知道如何使用下面的代码实现它，以便进度条（以及框架的其余部分）实际出现。

更新代码：

import java.awt.Toolkit;
import java.awt.event.WindowEvent;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextArea;
import javax.swing.JButton;
import javax.swing.JProgressBar;
import javax.swing.JLabel;

import org.apache.commons.io.FileUtils;

@SuppressWarnings("serial")
public class BasicCopy extends JFrame {

    private JPanel contentPane;
    private JTextArea txtCopiedDirs;
    private JButton btnCancel;
    private JProgressBar progressBar;
    private JLabel lblCopying;
    private String mainDrive;
    private String backupDrive;
    private String username;
    private String backupDir;
    long totalSize = 0; //total size of directories/files
    long currentSize = 0;   //current size of files counting up to ONE_PERCENT
    int currentPercent = 0; //current progress in %
    long ONE_PERCENT;       //totalSize / 100

    public BasicCopy() {
    }

    public BasicCopy(String inDrive, String outDrive, String username, long space){
        mainDrive = inDrive;
        backupDrive = outDrive;
        this.username = username;
        totalSize = space;
        ONE_PERCENT = totalSize/100;
        createGUI();

        /*  Should not have these here!
         *  Pretty sure I need a SwingWorker
         */
        createBackupDirectory();
        copyDirectories();
    }

    public void createGUI(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Backup Progress");
        setBounds(100, 100, 450, 300);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        txtCopiedDirs = new JTextArea();
        txtCopiedDirs.setBounds(10, 56, 414, 125);
        contentPane.add(txtCopiedDirs);

        btnCancel = new JButton("Cancel");
        btnCancel.setBounds(169, 227, 89, 23);
        contentPane.add(btnCancel);

        progressBar = new JProgressBar(0, 100);
        progressBar.setBounds(10, 192, 414, 24);
        progressBar.setValue(0);
        contentPane.add(progressBar);

        lblCopying = new JLabel("Now backing up your files....");
        lblCopying.setBounds(10, 11, 157, 34);
        contentPane.add(lblCopying);

        setVisible(true);
    }

    //Create backup directory
    public void createBackupDirectory(){
        Date date = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("MM-dd-yyyy_HMMSS");
        String timestamp = sdf.format(date);
        backupDir = backupDrive + ":\\" + "Backup " + timestamp;
        File backupDirectory = new File(backupDir);
        backupDirectory.mkdir();
    }

    public void copyDirectories(){
        //Main directories
        String pics = mainDrive + ":\\Users\\" + username + "\\Pictures";
        String docs = mainDrive + ":\\Users\\" + username + "\\Documents";
        String vids = mainDrive + ":\\Users\\" + username + "\\Videos";
        String musc = mainDrive + ":\\Users\\" + username + "\\Music";
        //Backup directories
        String bkPics = backupDir + "\\Pictures";
        String bkDocs = backupDir + "\\Documents";
        String bkVids = backupDir + "\\Documents";
        String bkMusc = backupDir + "\\Pictures";

        String[] directories = {pics, docs, vids, musc};
        String[] bkDirectories = {bkPics, bkDocs, bkVids, bkMusc};

        //Loop through directories and copy files
        for (int i = 0; i < directories.length; i++){
            File dir = new File(directories[i]);
            File dest = new File(bkDirectories[i]);
            for(File file: dir.listFiles()){
                try{
                    FileUtils.copyDirectory(file, dest);
                    if(getDirSize(file) >= ONE_PERCENT){
                        currentPercent++;
                        progressBar.setValue(currentPercent);
                        currentSize = 0;
                    } else {
                        currentSize = currentSize + getDirSize(file);
                        if(currentSize >= ONE_PERCENT){
                            currentPercent++;
                            progressBar.setValue(currentPercent);
                            currentSize = 0;
                        }
                    }
                } catch (IOException e){
                    e.printStackTrace();
                }
            }
        }
    }

    public static Long getDirSize(File directory) {
        long size = 0L;

        if (directory.listFiles() != null){       
            for (File file : directory.listFiles()) {
                size += file.isDirectory() ? getDirSize(file) : file.length();
            }
        }
        return size;
    }

    /* Close current window */
    public void closeWindow() {
        WindowEvent close = new WindowEvent(this, WindowEvent.WINDOW_CLOSING);
        Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(close);
        System.exit(0);
    }
}