java GUI简单记事本

代码：

import java.awt.*;
import java.awt.event.*;
import java.io.*;
class MyMenu
{
    //定义该窗体所需的组件，方便其他函数引用
    private Frame f;
    private Button btn;  //按钮
    private Button btn1;
    private Label label; //标签
    private TextArea ta ; //文本区域
    private Menu fileMenu; //菜单
    private MenuBar bar;
    private MenuItem openItem,saveItem,closeItem; //子菜单
    
    private FileDialog openDia,saveDia; //文件对话框
    private File file; //文件
    //构造器
    MyMenu(){
        init();
    }
    public void init(){
        f = new Frame("我的窗体及菜单框架");
        /*（所有静态属性设置)*/
        //对窗体进行基本设置
        f.setBounds(100,50,1200,1000);
        f.setLayout(new FlowLayout());
        f.setBackground(Color.gray);
        //组件(自定义)
        btn      = new Button("退出");
        btn1  = new Button("按钮1");
        label = new Label("这是一个文本",Label.CENTER);
        ta = new TextArea("test",30,70,1);//最后一个参数设置为显示滚动条，1显示垂直滚动条，2显示横向滚动条，0全部显示。

        bar = new MenuBar();
        fileMenu = new Menu("文件");
        //定义菜单项
        openItem = new MenuItem("打开");
        saveItem = new MenuItem("保存");
        closeItem = new MenuItem("退出");
        //将菜单项添加进菜单
        fileMenu.add(openItem);
        fileMenu.add(saveItem);
        fileMenu.addSeparator();
        fileMenu.add(closeItem);
         //将菜单已添加进菜单栏
        bar.add(fileMenu);
        f.setMenuBar(bar);
        //添加文件对话框
        openDia = new FileDialog(f,"我要打开",FileDialog.LOAD);
        saveDia = new FileDialog(f,"我要保存",FileDialog.SAVE);
        //组件属性设置
        label.setBackground(Color.pink);
        label.setFont(new Font("Dialog", Font.BOLD, 12));
        label.setSize(300,200);
        //将组件添加到frame中
        f.add(label);
        f.add(ta);
        f.add(btn);
        f.add(btn1);
        //加载窗体事件（所有响应事件)
        myEvent();

        //显示窗体
        f.setVisible(true);
    }

    private void myEvent(){
        /*规则：
          xxxListener(new xxxAdapter())
                    xxxEvent e
        */
        //窗体关闭事件
        f.addWindowListener(new WindowAdapter()
        {
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
        //按钮响应事件
        btn.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e)
            {
                //按钮响应
                System.out.println("退出，按钮干的");
                System.exit(0);
            }
        });
        //按钮1响应事件
        btn1.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e)
            {
                //获取文本内容并显示
                String taContent =ta.getText();
                label.setText(taContent);
            }
        });
        //菜单事件：添加保存活动监听，
        saveItem.addActionListener(new ActionListener()
        {
        
            public void actionPerformed(ActionEvent e)
            {    
                //保存就是直接开启对话框
                //if(file==null)
                //{
                    saveDia.setVisible(true);

                    String dirPath = saveDia.getDirectory();
                    String fileName = saveDia.getFile();
                    if(dirPath==null || fileName==null)
                        return ;
                    file = new File(dirPath,fileName);
                //}

                try
                {
                    BufferedWriter bufw  = new BufferedWriter(new FileWriter(file));

                    String text = ta.getText();

                    bufw.write(text);
                    //bufw.flush();
                    bufw.close();
                }
                catch (IOException ex)
                {
                    throw new RuntimeException();
                }
                
            }
        });


        openItem.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                openDia.setVisible(true);
                String dirPath = openDia.getDirectory();
                String fileName = openDia.getFile();
//                System.out.println(dirPath+"..."+fileName);
                if(dirPath==null || fileName==null)
                    return ;

                ta.setText("");
                file = new File(dirPath,fileName);

                try
                {
                    BufferedReader bufr = new BufferedReader(new FileReader(file));

                    String line = null;

                    while((line=bufr.readLine())!=null)
                    {
                        ta.append(line+"
");
                    }

                    bufr.close();
                }
                catch (IOException ex)
                {
                    throw new RuntimeException("读取失败");
                }


            }
        });





        closeItem.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                System.exit(0);
            }
        });
    }

    public static void main(String[] args){
        new MyMenu();
    }
}

效果：