java - JFileChooser 和复制文件

Question

我正在做一项类作业，有几个问题希望得到帮助。该分配是一个 GUI，允许用户选择要复制的文件并选择要将文件复制到的位置。

我已经完成了作业，但有几件事我想看看是否可以改变......

选择源文件时，我只想在标签中显示源文件的名称，但是程序需要整个路径才能复制文件，并且每次我尝试将其切换到仅显示文件名程序将不会运行，因为它不知道文件所在的位置。第二个问题，是否有办法让程序自动将文件复制为 .bak 文件...假设源文件是文本文件，用户选择目标文件夹并点击复制，它会保存一个具有相同名称的文件，但.bak 扩展名？

我将有问题的代码放在 *** 之间，并留下了我试图仅用于显示文件名的代码并将其注释掉。感谢您的帮助!!

public class CopyFile extends JFrame{

private JFileChooser fc;
private JButton copyButton;
private JButton chooseFileButton;
private JButton destinationButton;
private File workingDirectory;
private JLabel sourceLabel;
private JLabel destinationLabel;
private JTextField sourceText;
private JTextField sourceFileText;
private JTextField destinationText;

public static void main(String [] args) {
    CopyFile go = new CopyFile();
    go.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    go.setSize(500, 150);
    go.setVisible(true);
}

public CopyFile() {
    super("Copy a text file");
    setLayout(new GridLayout(3, 3, 5, 5));
    fc = new JFileChooser();

    //Open dialog box inside project folder to make easier to find files
    workingDirectory = new File(System.getProperty("user.dir"));
    fc.setCurrentDirectory(workingDirectory);
    //create labels and buttons for window
    chooseFileButton = new JButton("CHOOSE SOURCE FILE");
    destinationButton = new JButton("DESTINATION FOLDER");
    copyButton = new JButton("COPY FILE");      
    sourceLabel = new JLabel("SOURCE FILE: ");
    sourceText = new JTextField(10);
    sourceText.setEditable(false);
    destinationLabel = new JLabel("DESTINATION: ");
    destinationText = new JTextField(10);

    //add everything to JFrame  
    add(sourceLabel);
    add(sourceText);
    add(chooseFileButton);  
    add(destinationLabel);
    add(destinationText);
    add(destinationButton);
    add(copyButton);

    //Create TheHandler object to add action listeners for the buttons.
    TheHandler handler = new TheHandler();
    chooseFileButton.addActionListener(handler);
    destinationButton.addActionListener(handler);
    copyButton.addActionListener(handler);
}

//Inner class to create action listeners    
private class TheHandler implements ActionListener {
    public void actionPerformed(ActionEvent event) {
        int returnVal;
        String selectedFilePath;
        File selectedFile;

******************************************************************************      
        //Selecting a source file and displaying what the user is doing.
        if(event.getSource() == chooseFileButton) {     
            returnVal = fc.showOpenDialog(null);
            //Set the path for the source file. 
            if(returnVal == JFileChooser.APPROVE_OPTION) {  

  /*The two next lines of code are what I was trying to do to get only the
  file name but I get a whole page of errors, mainly I think it's saying no 
  such file exists*/
                //selectedFile = fc.getSelectedFile();
                //sourceText.setText(selectedFile.getName());   
                selectedFilePath = fc.getSelectedFile().getAbsolutePath();
                sourceText.setText(selectedFilePath);
            }       
        }//end if

******************************************************************************          
        //Handle destination button.
        if(event.getSource() == destinationButton) {
            returnVal = fc.showSaveDialog(null);
            if(returnVal == JFileChooser.APPROVE_OPTION) {
                 selectedFilePath = fc.getSelectedFile().getAbsolutePath();
                destinationText.setText(selectedFilePath);
            }               
        }//end if

        //Handle copy button
        if(event.getSource() == copyButton) {
            File sourceFile = new File(sourceText.getText());
            File destinationFile = new File(destinationText.getText());
            Path sourcePath = sourceFile.toPath();
            Path destinationPath = destinationFile.toPath();        
            try {
                Files.copy(sourcePath,  destinationPath);
            } catch (IOException e) {
                e.printStackTrace();
            }   
        }//end if

    }//end actionPerformed      
}//end TheHandler class
}//end class

Answer 1

You have to keep the source and destination file paths as Files, not Strings. Modify your code of TheHandler class as follows.

1. 添加 selectedSourceFile 和 selectedDestinationFile 本地字段。

   private class TheHandler implements ActionListener {
       private File selectedSourceFile;
       private File selectedDestinationFile;
   

2. 选择文件时更新它们并设置文件名而不是文本字段的路径。

源文件按钮

        if (event.getSource() == chooseFileButton) {
            returnVal = fc.showOpenDialog(null);
            if (returnVal == JFileChooser.APPROVE_OPTION) {
                selectedSourceFile = fc.getSelectedFile();
                sourceText.setText(selectedSourceFile.getName());
            }
        }

目的地按钮

        if (event.getSource() == destinationButton) {
            returnVal = fc.showSaveDialog(null);
            if (returnVal == JFileChooser.APPROVE_OPTION) {
                selectedDestinationFile = fc.getSelectedFile();
                destinationText.setText(selectedDestinationFile.getName());
            }
        }

复制时使用 selectedSourceFile 和 selectedDestinationFile。

    if (event.getSource() == copyButton) {
        Path sourcePath = selectedSourceFile.toPath();
        Path destinationPath = selectedDestinationFile.toPath();
        try {
            Files.copy(sourcePath, destinationPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Now you are done the first requirement. You can make backfile when selecting the destination file. So, add your code to make backup file when selecting destination button.

        if (event.getSource() == destinationButton) {
            returnVal = fc.showSaveDialog(null);
            if (returnVal == JFileChooser.APPROVE_OPTION) {
                selectedDestinationFile = fc.getSelectedFile();
                destinationText.setText(selectedDestinationFile.getName());

                //copy backup
                String name = selectedSourceFile.getName();
                name = selectedSourceFile.getName().substring(0, name.lastIndexOf(".")) + ".bak";
                File destinationFile = new File(selectedDestinationFile.getParentFile(), name);
                try {
                    Files.copy(selectedSourceFile.toPath(), destinationFile.toPath());
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }