Java摇摆 | JFileChooser

JFileChooser 是Java Swing 包的一部分。 Java Swing 包是 JavaTM Foundation Classes(JFC) 的一部分。 JFC 包含许多有助于在Java中构建图形用户界面的特性。 Java Swing 提供了按钮、面板、对话框等组件。 JFileChooser 是一种提示用户选择文件或目录的简单而有效的方法。
在本文中，我们将了解如何在Java swing 中使用 JFileChooser。
JFileChooser 的构造函数是：

1. JFileChooser() - 指向用户默认目录的空构造函数

Java

// Using this process to invoke the constructor,
// JFileChooser points to user's default directory
JFileChooser j = new JFileChooser();
 
// Open the save dialog
j.showSaveDialog(null);

代码片段的输出：

2. JFileChooser(String) – 使用给定的路径

Java

// Using this process to invoke the constructor,
// JFileChooser points to the mentioned path
JFileChooser j = new JFileChooser("d:");
 
// Open the save dialog
j.showSaveDialog(null);

代码片段的输出：

3. JFileChooser(File) – 使用给定的文件作为路径

Java

// Using this process to invoke the constructor,
// JFileChooser points to the mentioned path
// of the file passed
JFileChooser j = new JFileChooser(new File("C:\\Users\\pc\\Documents\\New folder\\"));
 
// Open the save dialog
j.showSaveDialog(null);

代码片段的输出：

4. JFileChooser(FileSystemView) – 使用给定的 FileSystemView

Java

// In this process argument passed
// is an object of File System View
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView());
 
// Open the save dialog
j.showSaveDialog(null);

代码片段的输出：

5. JFileChooser(String, FileSystemView) – 使用给定的路径和 FileSystemView

Java

// In this process argument passed is an object
// of File System View, and a path
JFileChooser j = new JFileChooser("d:", FileSystemView.getFileSystemView());
 
// Open the save dialog
j.showSaveDialog(null);

代码片段的输出：

6. JFileChooser(File, FileSystemView) – 使用给定的当前目录和 FileSystemView

Java

// In this process argument passed is an object
// of File System View and a object of
// File class
File f = new File("C:\\Users\\pc\\Documents\\New folder\\");
JFileChooser j = new JFileChooser(f, FileSystemView.getFileSystemView());
 
// Open the save dialog
j.showSaveDialog(null);

代码片段的输出：

注意：上面给出的代码是代码片段而不是完整的代码，上面给出的代码片段应该根据程序员的需要和判断来调用构造函数，上面提到的路径是任意的。用户应根据需要设置路径。

JFileChooser 的实际应用

以下代码不会在在线编译器中执行。请使用离线 IDE
1. 使用 JFileChooser 创建打开或保存对话框

Java

// Java program to create open or
// save dialog using JFileChooser
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
 
    // Jlabel to show the files user selects
    static JLabel l;
 
    // a default constructor
    filechooser()
    {
    }
 
    public static void main(String args[])
    {
        // frame to contains GUI elements
        JFrame f = new JFrame("file chooser");
 
        // set the size of the frame
        f.setSize(400, 400);
 
        // set the frame's visibility
        f.setVisible(true);
 
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // button to open save dialog
        JButton button1 = new JButton("save");
 
        // button to open open dialog
        JButton button2 = new JButton("open");
 
        // make an object of the class filechooser
        filechooser f1 = new filechooser();
 
        // add action listener to the button to capture user
        // response on buttons
        button1.addActionListener(f1);
        button2.addActionListener(f1);
 
        // make a panel to add the buttons and labels
        JPanel p = new JPanel();
 
        // add buttons to the frame
        p.add(button1);
        p.add(button2);
 
        // set the label to its initial value
        l = new JLabel("no file selected");
 
        // add panel to the frame
        p.add(l);
        f.add(p);
 
        f.show();
    }
    public void actionPerformed(ActionEvent evt)
    {
        // if the user presses the save button show the save dialog
        String com = evt.getActionCommand();
 
        if (com.equals("save")) {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // invoke the showsSaveDialog function to show the save dialog
            int r = j.showSaveDialog(null);
 
            // if the user selects a file
            if (r == JFileChooser.APPROVE_OPTION)
 
            {
                // set the label to the path of the selected file
                l.setText(j.getSelectedFile().getAbsolutePath());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
 
        // if the user presses the open dialog show the open dialog
        else {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // invoke the showsOpenDialog function to show the save dialog
            int r = j.showOpenDialog(null);
 
            // if the user selects a file
            if (r == JFileChooser.APPROVE_OPTION)
 
            {
                // set the label to the path of the selected file
                l.setText(j.getSelectedFile().getAbsolutePath());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
    }
}

2. 使用 JFileChooser 只选择目录

Java

// Java program to use JFileChooser
// to select  directory only
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
    // Jlabel to show the files user selects
    static JLabel l;
 
    // a default constructor
    filechooser()
    {
    }
 
    public static void main(String args[])
    {
        // frame to contains GUI elements
        JFrame f = new JFrame("file chooser to select directories");
 
        // set the size of the frame
        f.setSize(400, 400);
 
        // set the frame's visibility
        f.setVisible(true);
 
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // button to open save dialog
        JButton button1 = new JButton("save");
 
        // button to open open dialog
        JButton button2 = new JButton("open");
 
        // make an object of the class filechooser
        filechooser f1 = new filechooser();
 
        // add action listener to the button to capture user
        // response on buttons
        button1.addActionListener(f1);
        button2.addActionListener(f1);
 
        // make a panel to add the buttons and labels
        JPanel p = new JPanel();
 
        // add buttons to the frame
        p.add(button1);
        p.add(button2);
 
        // set the label to its initial value
        l = new JLabel("no file selected");
 
        // add panel to the frame
        p.add(l);
        f.add(p);
 
        f.show();
    }
    public void actionPerformed(ActionEvent evt)
    {
        // if the user presses the save button show the save dialog
        String com = evt.getActionCommand();
 
        if (com.equals("save")) {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // set the selection mode to directories only
            j.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
 
            // invoke the showsSaveDialog function to show the save dialog
            int r = j.showSaveDialog(null);
 
            if (r == JFileChooser.APPROVE_OPTION) {
                // set the label to the path of the selected directory
                l.setText(j.getSelectedFile().getAbsolutePath());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
        // if the user presses the open dialog show the open dialog
        else {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // set the selection mode to directories only
            j.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
 
            // invoke the showsOpenDialog function to show the save dialog
            int r = j.showOpenDialog(null);
 
            if (r == JFileChooser.APPROVE_OPTION) {
                // set the label to the path of the selected directory
                l.setText(j.getSelectedFile().getAbsolutePath());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
    }
}

3.使用JFileChooser允许多选文件

Java

// Java program to use JFileChooser to allow multiple selection of files
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
    // Jlabel to show the files user selects
    static JLabel l;
 
    // a default constructor
    filechooser()
    {
    }
 
    public static void main(String args[])
    {
        // frame to contains GUI elements
        JFrame f = new JFrame("file chooser to select multiple files at a time");
 
        // set the size of the frame
        f.setSize(400, 400);
 
        // set the frame's visibility
        f.setVisible(true);
 
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // button to open save dialog
        JButton button1 = new JButton("save");
 
        // button to open open dialog
        JButton button2 = new JButton("open");
 
        // make an object of the class filechooser
        filechooser f1 = new filechooser();
 
        // add action listener to the button to capture user
        // response on buttons
        button1.addActionListener(f1);
        button2.addActionListener(f1);
 
        // make a panel to add the buttons and labels
        JPanel p = new JPanel();
 
        // add buttons to the frame
        p.add(button1);
        p.add(button2);
 
        // set the label to its initial value
        l = new JLabel("no file selected");
 
        // add panel to the frame
        p.add(l);
        f.add(p);
 
        f.show();
    }
    public void actionPerformed(ActionEvent evt)
    {
        // if the user presses the save button show the save dialog
        String com = evt.getActionCommand();
 
        if (com.equals("save")) {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // allow multiple file selection
            j.setMultiSelectionEnabled(true);
 
            // invoke the showsSaveDialog function to show the save dialog
            int r = j.showSaveDialog(null);
 
            if (r == JFileChooser.APPROVE_OPTION) {
                // get the selelcted files
                File files[] = j.getSelectedFiles();
 
                int t = 0;
                // set text to blank
                l.setText("");
 
                // set the label to the path of the selected files
                while (t++ < files.length)
                    l.setText(l.getText() + " " + files[t - 1].getName());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
 
        // if the user presses the open dialog show the open dialog
        else {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // allow multiple file selection
            j.setMultiSelectionEnabled(true);
 
            // invoke the showsOpenDialog function to show the save dialog
            int r = j.showOpenDialog(null);
 
            if (r == JFileChooser.APPROVE_OPTION) {
                // get the selelcted files
                File files[] = j.getSelectedFiles();
 
                // set text to blank
                l.setText("");
 
                int t = 0;
                // set the label to the path of the selected files
                while (t++ < files.length)
                    l.setText(l.getText() + " " + files[t - 1].getName());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
    }
}

4. 使用 JFileChooser 限制向用户显示的文件类型

Java

// Java program to use JFileChooser to restrict
// the type of files shown to the user
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
    // Jlabel to show the files user selects
    static JLabel l;
 
    // a default constructor
    filechooser()
    {
    }
 
    public static void main(String args[])
    {
        // frame to contains GUI elements
        JFrame f = new JFrame("file chooser");
 
        // set the size of the frame
        f.setSize(400, 400);
 
        // set the frame's visibility
        f.setVisible(true);
 
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        // button to open save dialog
        JButton button1 = new JButton("save");
 
        // button to open open dialog
        JButton button2 = new JButton("open");
 
        // make an object of the class filechooser
        filechooser f1 = new filechooser();
 
        // add action listener to the button to capture user
        // response on buttons
        button1.addActionListener(f1);
        button2.addActionListener(f1);
 
        // make a panel to add the buttons and labels
        JPanel p = new JPanel();
 
        // add buttons to the frame
        p.add(button1);
        p.add(button2);
 
        // set the label to its initial value
        l = new JLabel("no file selected");
 
        // add panel to the frame
        p.add(l);
        f.add(p);
 
        f.show();
    }
    public void actionPerformed(ActionEvent evt)
    {
        // if the user presses the save button show the save dialog
        String com = evt.getActionCommand();
 
        if (com.equals("save")) {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // resctrict the user to select files of all types
            j.setAcceptAllFileFilterUsed(false);
 
            // set a title for the dialog
            j.setDialogTitle("Select a .txt file");
 
            // only allow files of .txt extension
            FileNameExtensionFilter restrict = new FileNameExtensionFilter("Only .txt files", "txt");
            j.addChoosableFileFilter(restrict);
 
            // invoke the showsSaveDialog function to show the save dialog
            int r = j.showSaveDialog(null);
 
            // if the user selects a file
            if (r == JFileChooser.APPROVE_OPTION)
 
            {
                // set the label to the path of the selected file
                l.setText(j.getSelectedFile().getAbsolutePath());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
        // if the user presses the open dialog show the open dialog
 
        else {
            // create an object of JFileChooser class
            JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
 
            // resctrict the user to select files of all types
            j.setAcceptAllFileFilterUsed(false);
 
            // set a title for the dialog
            j.setDialogTitle("Select a .txt file");
 
            // only allow files of .txt extension
            FileNameExtensionFilter restrict = new FileNameExtensionFilter("Only .txt files", "txt");
            j.addChoosableFileFilter(restrict);
 
            // invoke the showsOpenDialog function to show the save dialog
            int r = j.showOpenDialog(null);
 
            // if the user selects a file
            if (r == JFileChooser.APPROVE_OPTION) {
                // set the label to the path of the selected file
                l.setText(j.getSelectedFile().getAbsolutePath());
            }
            // if the user cancelled the operation
            else
                l.setText("the user cancelled the operation");
        }
    }
}

笔记 ：
您还可以使用函数setApproveButtonText(String) 自定义批准按钮。这将设置已批准按钮的文本
到所需的文本。