我敢肯定这个问题以前有人问过，但我找到的答案都不能很好地与我现有的代码一起使用。我会发布这个问题，以防有一种方法可以做到这一点，而无需完全重做我目前所做的一切。

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，旨在将图片、文档、视频和音乐文件夹(Windows 机器上的标准文件夹)的内容复制到第二个驱动器上备份目录中的同名文件夹。这是目前为止的类(class):

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);
    }
}

我在上一个类中有一个方法可以测量目录的总大小，因此如果需要我可以将它传递给这个类。但是，我目前只循环遍历四个目录，所以我预计我将无法以任何高于 25% 每次刻度的分辨率来增加进度条。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，并让它更准确一些？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它的速度？那部分不是优先事项。现在我主要对添加进度条感兴趣。干杯!

编辑:

经过一些调整后，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有效也可能无效——我只是快速记下它以免忘记它，它仍未经过测试)。这将允许我更新每个复制文件的进度条。

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，我相信我已经弄明白了大部分。现在的问题是关于 SwingWorker，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，这就是我卡住的地方。我以前只用过一次 SwingWorker，那主要是用复制的代码。我想知道如何使用以下代码实现它，以便实际显示进度条(和框架的其余部分)。

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);
    }
}

最佳答案

我找到了一个可行的解决方案。它仍然有一些小故障，但主要是不重要的细节。这是我现在所拥有的，它似乎在工作。

class Task extends SwingWorker<Void, Void>{
    @Override
    public Void doInBackground(){
        setProgress(0);

        //Create Backup Directory
        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();

        //Copy Files
        //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{
                    if(file.isFile()){
                        FileUtils.copyFileToDirectory(file, dest);
                        txtCopiedDirs.append(file.getAbsolutePath() + "\n");
                    } else if (file.isDirectory()){
                        FileUtils.copyDirectoryToDirectory(file, dest);
                        txtCopiedDirs.append(file.getAbsolutePath() + "\n");
                    }
                    if(getDirSize(file) >= ONE_PERCENT){
                        currentPercent = getDirSize(file)/ONE_PERCENT;
                        progressBar.setValue((int)currentPercent);
                        currentSize = 0;
                    } else {
                        currentSize = currentSize + getDirSize(file);
                        if(currentSize >= ONE_PERCENT){
                            currentPercent = currentSize/ONE_PERCENT;
                            currentPercent++;
                            progressBar.setValue((int)currentPercent);
                            currentSize = 0;
                        }
                    }
                } catch (IOException e){
                    e.printStackTrace();
                }
            }
        }

        return null;
    }
    @Override
    public void done(){
        closeWindow();
    }
}

此类包含在主类中，并使用以下代码启动:

Task task = new Task();
task.execute();

这会在框架创建并设置为可见后立即调用。

现在，正如我提到的，这仍然不完美。例如，在复制之前检查它是文件还是目录应该替换为递归函数，以便它循环遍历每个单独的文件，而不是如果目录是完整目录则只复制目录。这将允许更准确地更新进度条，并将在文本区域中显示正在复制的单个文件，而不是文件和目录。

无论如何，我只是想发布这段代码来展示对我有用的代码，而不是完全重做我已有的代码。不过，我会继续努力，并发布任何可能对 future 的读者有所帮助的重要更新。

感谢大家的回复，他们帮了大忙!

关于java - 使用 Java 复制文件时的进度条，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20767241/