Question

用java编写记事本只要有打开 保存和退出功能就行，代码越简单越好，谢谢

Answer 1

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JNotePadUI extends JFrame {
private JMenuItem menuOpen;
private JMenuItem menuSave;
private JMenuItem menuSaveAs;
private JMenuItem menuClose;
private JMenuItem menuChoose;
private JMenu editMenu;
private JMenuItem menuCut;
private JMenuItem menuCopy;
private JMenuItem menuPaste;
private JMenuItem menuAbout;
private JTextArea textArea;
private JLabel stateBar;
private JFileChooser fileChooser;
private JPopupMenu popUpMenu;
public JNotePadUI() {
super("新建文本文档-记事本");
setUpUIComponent();
setUpEventListener();
setVisible(true);
}
private void setUpUIComponent() {
setSize(640, 480);
// 菜单栏
JMenuBar menuBar = new JMenuBar();
// 设置「文件」菜单
JMenu fileMenu = new JMenu("文件");
menuOpen = new JMenuItem("打开");
// 快捷键设置
menuOpen.setAccelerator(
KeyStroke.getKeyStroke(
KeyEvent.VK_O,
InputEvent.CTRL_MASK));
menuSave = new JMenuItem("保存");
menuSave.setAccelerator(
KeyStroke.getKeyStroke(
KeyEvent.VK_S,
InputEvent.CTRL_MASK));
menuSaveAs = new JMenuItem("另存为");
menuChoose=new JMenuItem("全选");
menuChoose.setAccelerator(
KeyStroke.getKeyStroke(
KeyEvent.VK_A,
InputEvent.CTRL_MASK));
menuClose = new JMenuItem("关闭");
menuClose.setAccelerator(
KeyStroke.getKeyStroke(
KeyEvent.VK_Q,
InputEvent.CTRL_MASK));
fileMenu.add(menuOpen);
fileMenu.addSeparator(); // 分隔线
fileMenu.add(menuSave);
fileMenu.add(menuSaveAs);
fileMenu.addSeparator(); // 分隔线
fileMenu.add(menuChoose);
fileMenu.addSeparator();// 分隔线
fileMenu.add(menuClose);
// 设置「编辑」菜单
JMenu editMenu = new JMenu("编辑");
menuCut = new JMenuItem("剪切");
menuCut.setAccelerator(
KeyStroke.getKeyStroke(KeyEvent.VK_X,
InputEvent.CTRL_MASK));
menuCopy = new JMenuItem("复制");
menuCopy.setAccelerator(
KeyStroke.getKeyStroke(KeyEvent.VK_C,
InputEvent.CTRL_MASK));
menuPaste = new JMenuItem("粘贴");
menuPaste.setAccelerator(
KeyStroke.getKeyStroke(KeyEvent.VK_V,
InputEvent.CTRL_MASK));
editMenu.add(menuCut);
editMenu.add(menuCopy);
editMenu.add(menuPaste);
// 设置「关于」菜单
JMenu aboutMenu = new JMenu("关于");
menuAbout = new JMenuItem("关于记事本");
aboutMenu.add(menuAbout);
menuBar.add(fileMenu);
menuBar.add(editMenu);
menuBar.add(aboutMenu);
setJMenuBar(menuBar);
// 文字编辑区域
textArea = new JTextArea();
textArea.setFont(new Font("宋体", Font.PLAIN, 16));
textArea.setLineWrap(true);
JScrollPane panel = new JScrollPane(textArea,
ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
Container contentPane = getContentPane();
contentPane.add(panel, BorderLayout.CENTER);
// 状态栏
stateBar = new JLabel("未修改");
stateBar.setHorizontalAlignment(SwingConstants.LEFT);
stateBar.setBorder(
BorderFactory.createEtchedBorder());
contentPane.add(stateBar, BorderLayout.SOUTH);
popUpMenu = editMenu.getPopupMenu();
fileChooser = new JFileChooser();
}
private void setUpEventListener() {
// 按下窗口关闭钮事件处理
addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent e) {
closeFile();
}
}
);
// 菜单 - 打开
menuOpen.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
openFile();
}
}
);
// 菜单 - 保存
menuSave.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
saveFile();
}
}
);
// 菜单 - 另存为
menuSaveAs.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
saveFileAs();
}
}
);
// 菜单 -关闭
menuClose.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
closeFile();
}
}
);
// 菜单 - 剪切
menuCut.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
cut();
}
}
);
// 菜单 - 复制
menuCopy.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
copy();
}
}
);
// 菜单 - 粘贴
menuPaste.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
paste();
}
}
);
// 菜单 - 关于
menuAbout.addActionListener(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
// 显示对话框
JOptionPane.showOptionDialog(null,
"程序名称:\n JNotePad \n" +
"程序设计:\n ???\n" +
"简介:\n 一个简单的文字编辑器\n",
"关于JNotePad",
JOptionPane.DEFAULT_OPTION,
JOptionPane.INFORMATION_MESSAGE,
null, null, null);
}
}
);
// 编辑区键盘事件
textArea.addKeyListener(
new KeyAdapter() {
public void keyTyped(KeyEvent e) {
processTextArea();
}
}
);
// 编辑区鼠标事件
textArea.addMouseListener(
new MouseAdapter() {
public void mouseReleased(MouseEvent e) {
if(e.getButton() == MouseEvent.BUTTON3)
popUpMenu.show(editMenu, e.getX(), e.getY());
}
public void mouseClicked(MouseEvent e) {
if(e.getButton() == MouseEvent.BUTTON1)
popUpMenu.setVisible(false);
}
}
);
}
private void openFile() {
if(isCurrentFileSaved()) { // 文件是否为保存状态
open(); // 打开
}
else {
// 显示对话框
int option = JOptionPane.showConfirmDialog(
null, "文件已修改，是否保存？",
"保存文件？", JOptionPane.YES_NO_OPTION,
JOptionPane.WARNING_MESSAGE, null);
switch(option) {
// 确认文件保存
case JOptionPane.YES_OPTION:
saveFile(); // 保存文件
break;
// 放弃文件保存
case JOptionPane.NO_OPTION:
open();
break;
}
}
}
private boolean isCurrentFileSaved() {
if(stateBar.getText().equals("未修改")) {
return true;
}
else {
return false;
}
}
private void open() {
// fileChooser 是 JFileChooser 的实例
// 显示文件选取的对话框
int option = fileChooser.showDialog(null, null);

// 使用者按下确认键
if(option == JFileChooser.APPROVE_OPTION) {
/*
TODO: 添加读取文件的代码
*/
}
}
private void saveFile() {
/*
TODO: 添加保存文件的代码
*/
}

private void saveFileAs() {
/*
TODO: 添加另存为的代码
*/
}

private void closeFile() {
// 是否保存文件
if(isCurrentFileSaved()) {
// 释放窗口资源，而后关闭程序
dispose();
}
else {
int option = JOptionPane.showConfirmDialog(
null, "文件已修改，是否保存？",
"保存文件？", JOptionPane.YES_NO_OPTION,
JOptionPane.WARNING_MESSAGE, null);
switch(option) {
case JOptionPane.YES_OPTION:
saveFile();
break;
case JOptionPane.NO_OPTION:
dispose();
}
}
}
private void cut() {
textArea.cut();
stateBar.setText("已修改");
popUpMenu.setVisible(false);
}
private void copy() {
textArea.copy();
popUpMenu.setVisible(false);
}
private void paste() {
textArea.paste();
stateBar.setText("已修改");
popUpMenu.setVisible(false);
}
private void processTextArea() {
stateBar.setText("已修改");
}
public static void main(String[] args) {
new JNotePadUI();
}

Answer 2

文件名：jtxtfm.java
保存时文件名如file.txt 文件格式也要输入
！！！注意该程序只能打开txt文件、java源程序文件、html文件等,
Word的doc文件是特殊格式文件不能用本程序打开。

import java.io.*;
import java.awt.*;
import java.awt.event.*;

public class jtxtfm{
public static void main(String args[]){
jtxtfrm fm=new jtxtfrm();
}
}

class jtxtfrm extends Frame implements ActionListener{
FileDialog op,sv;
Button btn1,btn2,btn3;
TextArea tarea;
jtxtfrm(){
super("读写文件");
setLayout(null);
setBackground(Color.cyan);
setSize(600,300);
setVisible(true);
btn1=new Button("打开");
btn2=new Button("保存");
btn3=new Button("关闭");
tarea=new TextArea("");
add(btn1);add(btn2);add(btn3);add(tarea);
tarea.setBounds(30,50,460,220);
btn1.setBounds(520,60,50,30);
btn2.setBounds(520,120,50,30);
btn3.setBounds(520,180,50,30);
op=new FileDialog(this,"打开",FileDialog.LOAD);
sv=new FileDialog(this,"保存",FileDialog.SAVE);
btn1.addActionListener(this);
btn2.addActionListener(this);
btn3.addActionListener(this);
addWindowListener(
new WindowAdapter(){
public void windowClosing(WindowEvent e){
setVisible(false);
System.exit(0);
}
}
);
}

public void actionPerformed(ActionEvent e){
if(e.getSource()==btn1){
String str;
op.setVisible(true);
try{
File f1=new File(op.getDirectory(),op.getFile());
FileReader fr=new FileReader(f1);
BufferedReader br=new BufferedReader(fr);
tarea.setText("");
while((str=br.readLine())!=null)tarea.append(str+'\n');
fr.close();
}
catch(Exception e1)
{}
}

if(e.getSource()==btn2){
sv.setVisible(true);
try{
File f1=new File(sv.getDirectory(),sv.getFile());
FileWriter fw=new FileWriter(f1);
BufferedWriter bw=new BufferedWriter(fw);
String gt=tarea.getText();
bw.write(gt,0,gt.length());
bw.flush();
fw.close();
}
catch ( Exception e2)
{}
}

if(e.getSource()==btn3){
System.exit(0);
}

}
}

Answer 3

public class A{
public static void maid(string[] args){
System.out.println("你好!");
}
}
保存为A.java。