Java Swing开发简易记事本

GUI

创建主窗口

Java中的JFrame的概述、常用方法、实现案例-优快云博客

import javax.swing.JFrame;

public class SimpleNotepad {
    private JFrame frame;

    public SimpleNotepad() {
        frame = new JFrame("简易记事本");
        frame.setSize(800, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public void showWindow() {
        frame.setVisible(true);
    }
}

添加文本区域

import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class SimpleNotepad {
    // ... 前面的代码

    private JTextArea textArea;

    public SimpleNotepad() {
        // ... 前面的代码

        textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);
        frame.add(scrollPane);
    }

    // ... 后面的代码
}

创建菜单栏

import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;

public class SimpleNotepad {
    // ... 前面的代码

    private JMenuBar menuBar;
    private JMenu fileMenu, editMenu;
    private JMenuItem newFileItem, openFileItem, saveFileItem;

    public SimpleNotepad() {
        // ... 前面的代码

        menuBar = new JMenuBar();
        fileMenu = new JMenu("文件");
        editMenu = new JMenu("编辑");

        newFileItem = new JMenuItem("新建");
        openFileItem = new JMenuItem("打开...");
        saveFileItem = new JMenuItem("保存");

        fileMenu.add(newFileItem);
        fileMenu.add(openFileItem);
        fileMenu.add(saveFileItem);

        menuBar.add(fileMenu);
        menuBar.add(editMenu);

        frame.setJMenuBar(menuBar);
    }

    // ... 后面的代码
}

实现菜单项功能

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class SimpleNotepad {
    // ... 前面的代码

    public SimpleNotepad() {
        // ... 前面的代码

        newFileItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                textArea.setText("");
            }
        });

        openFileItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // Implement opening a file here
            }
        });

        saveFileItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                // Implement saving a file here
            }
        });
    }

    // ... 后面的代码
}

文件打开与保存功能

JFileChooser (Java Swing提供的文件选择对话框)_setfileselectionmode-优快云博客

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import java.io.File;

public class FileChooserExample {

    public void openFile(JFrame frame) {
        JFileChooser fileChooser = new JFileChooser();
        int result = fileChooser.showOpenDialog(frame); // 显示文件打开对话框

        switch (result) {
            case JFileChooser.APPROVE_OPTION:
                File selectedFile = fileChooser.getSelectedFile(); // 获取用户选择的文件
                System.out.println("Selected file: " + selectedFile.getAbsolutePath());
                break;
            case JFileChooser.CANCEL_OPTION:
                System.out.println("Open command cancelled by user.");
                break;
            case JFileChooser.ERROR_OPTION:
                System.out.println("Error in opening file dialog.");
                break;
            default:
                // Handle other cases if necessary.
        }
    }
}

完整代码

package GUI;

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;

public class NoteJFrame {
    private JFrame frame;
    private JTextArea textArea;
    private JScrollPane scrollPane;
    //菜单栏
    private JMenuBar menuBar;
    private JMenu fileMenu;

    private JMenuItem newFileItem,openFileItem,saveFileItem;


    public NoteJFrame(){
        frame = new JFrame("简易记事本");
        frame.setSize(800,600);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        // 添加文本区域
        textArea = new JTextArea();
        scrollPane = new JScrollPane(textArea);
        frame.add(scrollPane);

        //菜单栏
        menuBar = new JMenuBar();

        fileMenu = new JMenu("文件");

        newFileItem = new JMenuItem("新建");
        openFileItem = new JMenuItem("打开");
        saveFileItem = new JMenuItem("保存");

        fileMenu.add(newFileItem);
        fileMenu.add(openFileItem);
        fileMenu.add(saveFileItem);

        menuBar.add(fileMenu);

        frame.setJMenuBar(menuBar);
        //添加菜单功能
        newFileItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                textArea.setText("");
            }
        });
        openFileItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                JFileChooser fileChooser = new JFileChooser();
                int result = fileChooser.showOpenDialog(null);
                if (result == JFileChooser.APPROVE_OPTION){
                    File selectedFile = fileChooser.getSelectedFile();
                    try(BufferedReader br = new BufferedReader(new FileReader(selectedFile))) {

                        StringBuilder content = new StringBuilder();
                        String line;
                        while((line = br.readLine())!=null){
                            content.append(line).append("\n");
                        }
                        textArea.setText(content.toString());
                    } catch (FileNotFoundException ex) {
                        throw new RuntimeException(ex);
                    } catch (IOException ex) {
                        throw new RuntimeException(ex);
                    }

                }
            }
        });
        saveFileItem.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                JFileChooser fileChooser = new JFileChooser();
                int result = fileChooser.showSaveDialog(null);
                if(result == JFileChooser.APPROVE_OPTION){
                    File selectedFile = fileChooser.getSelectedFile();
                    try (BufferedWriter bw = new BufferedWriter(new FileWriter(selectedFile))){
                        bw.write(textArea.getText());
                    } catch (IOException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        });

    }

    public void showWindow(){
        frame.setVisible(true);

    }

}

Main.class

import GUI.NoteJFrame;

import javax.swing.*;

public class Main {
    public static void main(String[] args) {
        NoteJFrame noteJFrame = new NoteJFrame();
        noteJFrame.showWindow();


    }
}