4. 怎样用JAVA编写一个记事本程序 /***题目：记事本程序*Author: Jeason** 2004-12-20***/package jeason;import java.awt.*;import java.awt.event.*;import javax.swing.*;import javax.swing.event.*;import java.io.*;import java.util.*;import java.text.*;public class Jsb{///boolean dirty=true;String filename="";String strtext="";///////////////////////////////////////////// Menu ///////////////////////////////////////JFrame frame=new JFrame（"我的记事本"）；JPopupMenu pop=new JPopupMenu（"弹出"）；JTextArea text=new JTextArea();JLabel statubar=new JLabel（"状态栏"）；JMenuBar Mbar=new JMenuBar();JFileChooser jFileChooser1=new JFileChooser();JColorChooser jColor=new JColorChooser();JMenu jFile=new JMenu（"文件"）；JMenu jEdit=new JMenu（"编辑"）；JMenu jFormat=new JMenu（"格式"）；JMenu jHelp=new JMenu（"帮助"）；JMenuItem jnew=new JMenuItem（"新建（N）");public Jsb（){ ///无参数的构造函数///this.dirty=false;/////final BorderLayout borderLayout1=new BorderLayout();frame.setSize(600,500);//frame.addWindowListener(new Jsb_frame_closingAdapter(this));JPanel panel=new JPanel();panel.setLayout(borderLayout1)；//布局panel.add(new JScrollPane(text)）；//滚动条panel.add(statubar,borderLayout1.SOUTH);frame.getContentPane().add(panel);//frame.setJMenuBar(Mbar)； //将主菜单添加到窗体中/** jnew**/ //jnewjnew.addActionListener(new File_new_actionAdapter(this));jnew.setMnemonic（′N′）；//N上下划线jnew.setAccelerator(KeyStroke.getKeyStroke（′N′，java.awt.Event.CTRL_MASK,true））；//快捷方式/* * jopen**/JMenuItem jopen=new JMenuItem（"打开（O）");//jopenjopen.addActionListener(new File_open_actionAdapter(this));jopen.setMnemonic（′O′）；jopen.setAccelerator(KeyStroke.getKeyStroke（′O′，java.awt.Event.CTRL_MASK,true）);/** jsave**/JMenuItem jsave=new JMenuItem（"保存（S）");jsave.addActionListener(new File_save_actionAdapter(this));jsave.setMnemonic（′S′）；jsave.setAccelerator(KeyStroke.getKeyStroke（′S′，java.awt.Event.CTRL_MASK,true）);/** jsave as**/JMenuItem jsaveas=new JMenuItem（"另存为 。
"）；jsaveas.addActionListener(new File_saveas_actionAdapter(this));/** jquite**/JMenuItem jquite=new JMenuItem（"关闭（Q）");jquite.addActionListener(new File_quite_actionAdapter(this));jquite.setMnemonic（′Q′）；jquite.setAccelerator(KeyStroke.getKeyStroke（′Q′，java.awt.Event.CTRL_MASK,true）);//------------------------------------// jFile code of end//--------------------------------------/*** jEdit code*///jundoJMenuItem jundo=new JMenuItem（"撤销（U）");jundo.addActionListener(new Edit_undo_actionAdapter(this));jundo.setMnemonic（′U′）；jundo.setAccelerator(KeyStroke.getKeyStroke（′U′，java.awt.Event.CTRL_MASK,true）);/** jcut**/JMenuItem jcut=new JMenuItem（"剪切（X）");jcut.addActionListener(new Edit_cut_actionAdapter(this));jcut.setMnemonic（′X′）；jcut.setAccelerator(KeyStroke.getKeyStroke（′X′，java.awt.Event.CTRL_MASK,true）);/** jcopy**/JMenuItem jcopy=new JMenuItem（"复制（C）");jcopy.addActionListener(new Edit_copy_actionAdapter(this));jcopy.setMnemonic（′C′）；jcopy.setAccelerator(KeyStroke.getKeyStroke（′C′，java.awt.Event.CTRL_MASK,true）);/** jpaste**/JMenuItem jpaste=new JMenuItem（"粘贴（V）");jpaste.addActionListener(new Edit_paste_actionAdapter(this));jpaste.setMnemonic（′V′）；jpaste.setAccelerator(KeyStroke.getKeyStroke（′V′，java.awt.Event.CTRL_MASK,true）);/** jdelete**/ JMenuItem jdelete=new JMenuItem（"删除（D）");jdelete.addActionListener(new Edit_delete_actionAdapter(this));jdelete.setMnemonic（′D′）；jdelete.setAccelerator(KeyStroke.getKeyStroke（′D′，java.awt.Event.CTRL_MASK,true）);/** jfind**/ JMenuItem jfind=new JMenuItem（"查找（F）");jfind.addActionListener(new Edit_find_actionAdapter(this));jfind.setMnemonic（′F′）；jfind.setAccelerator(KeyStroke.getKeyStroke（′F′，java.awt.Event.CTRL_MASK,true）);/** jreplace**/JMenuItem jreplace=new JMenuItem（"替换（R）");jreplace.addActionListener(new Edit_replace_actionAdapter(this));jreplace.setMnemonic（′R′）；jreplace.setAccelerator(KeyStroke.getKeyStroke（′R′，java.awt.Event.CTRL_MASK,true）);/**jselectall**/JMenuItem jselectall=new JMenuItem（"全选（A）");jselectall.addActionListener(new Edit_selectall_actionAdapter(this));jselectall.setMnemonic（′A′）；jselectall.setAccelerator(KeyStroke.getKeyStroke（′A′，java.awt.Event.CTRL_MASK,true）);/** jdate**/JMenuItem jdate=new JMenuItem（"日期/时间（T）");jdate.addActionListener(new Edit_timedate_actionAdapter( 。