GUI——练习（打开保存文件）

package mymenu;import java.awt.*;import java.awt.event.*;import java.io.*;public class MyMenuTest{private Frame f;private MenuBar bar;private TextArea ta;private Menu fileMenu;private MenuItem openItem,saveItem,closeItem;private FileDialog openDia,saveDia;private File file;MyMenuTest(){init();}public void init(){f = new Frame("my window");f.setBounds(300,100,650,600);bar = new MenuBar();ta = new TextArea();fileMenu = new Menu("文件");openItem = new MenuItem("打开");saveItem = new MenuItem("保存");closeItem = new MenuItem("退出");fileMenu.add(openItem);fileMenu.add(saveItem);fileMenu.add(closeItem);bar.add(fileMenu);f.setMenuBar(bar);openDia = new FileDialog(f,"我要打开",FileDialog.LOAD);saveDia = new FileDialog(f,"我要保存",FileDialog.SAVE);f.add(ta);myEvent();f.setVisible(true);}private void myEvent(){saveItem.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){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+"\r\n");}bufr.close();}catch (IOException ex){throw new RuntimeException("读取失败");}}});closeItem.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){System.exit(0);}});f.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}});}public static void main(String[] args) {new MyMenuTest();}}/*如何制作可以双击执行的jar包呢？1，将多个类封装到了一个包(package)中。2，定义一个jar包的配置信息。定义一个文件a.txt 。文件内容内容为：Main-Class:(空格)包名.类名(回车)3，打jar包。jar -cvfm my.jar a.txt 包名4，通过winrar程序进行验证，查看该jar的配置文件中是否有自定义的配置信息。5，通过工具--文件夹选项--文件类型--jar类型文件，通过高级，定义该jar类型文件的打开动作的关联程序。jdk\bin\javaw.exe -jar6，双击试试！。哦了。*/