java writing notepad

import java.awt.FileDialog;
import java.awt.FlowLayout;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
 
 
public class Not implements ActionListener, MouseListener {
private ArrayList<String> al = new ArrayList<String>();
private int set = 0;
private JFrame jf = new JFrame("Notepad");
private JTextArea jta = new JTextArea(20,40);
JScrollPane jsp = new JScrollPane(jta);
private JTextField jtf = new JTextField(10);
private JTextField jtft = new JTextField(10);
private JPopupMenu pp = new JPopupMenu();
private String target = null;
private JDialog jd = new JDialog(jf, "警告");
 
public void actionPerformed(ActionEvent e) {
String comm = e.getActionCommand();
if (comm.equals("新建...")) {
 
if(!jta.getText().equals("")){
jd.setLocation(300, 300);
jd.setVisible(true);
}else{
jta.setText("1234548882");
}
}
if(comm.equals("否")){
jta.setText("");
jd.dispose(); 
} 
if(comm.equals("取消")){
jd.dispose(); 
}
if (comm.equals("保存") || comm.equals("另存...")||comm.equals("是")) {
if(comm.equals("是")) jd.dispose();
FileDialog fd = new FileDialog(jf, "打开...", FileDialog.SAVE);
fd.setFilenameFilter(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.endsWith(".txt") || name.endsWith(".java");
}
});
if (target == null || "另存...".equals(comm)) {
fd.setVisible(true);
}
if (fd.getFile() != null) {
target = fd.getFile();
try {
FileOutputStream fos = new FileOutputStream(fd
.getDirectory()
+ target);
byte[] b = jta.getText().getBytes();
for (byte by : b) {
fos.write(by);
}
fos.close();
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
if (comm.equals("打开...")) {
al.add(jta.getText());
FileDialog fd = new FileDialog(jf, "打开...", FileDialog.LOAD);
fd.setFilenameFilter(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.endsWith(".txt") || name.endsWith(".java");
}
});
fd.setVisible(true);
// 以下是打开文件
target = fd.getFile();
String str = fd.getDirectory() + target;
if (fd.getFile() != null) {
try {
String res = "";
FileInputStream fis = new FileInputStream(str);
byte[] b = new byte[1024];
int count;
while ((count = fis.read(b)) != -1) {
res = res + new String(b, 0, count);
}
fis.close();
jta.setText(res);
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
if (comm.equals("退出")) {
System.exit(0);
}
if (comm.equals("撤销")) {
if(!al.isEmpty()){
jta.setText(al.get(al.size()-1));
al.remove(al.size()-1);
}
}
if (comm.equals("剪切")) {
al.add(jta.getText());
jta.cut();
}
if (comm.equals("复制")) {
al.add(jta.getText());
jta.copy();
}
if (comm.equals("粘贴")) {
al.add(jta.getText());
jta.paste();
}
if (comm.equals("删除")) {
al.add(jta.getText());
jta.cut();
}
if ("查找...".equals(comm) || "替换...".equals(comm)) {
JDialog jdct = new JDialog(jf,comm);
 
String label = comm.substring(0, 2);
JButton jb = new JButton(label);
jb.addActionListener(this);
jdct.setLayout(new FlowLayout());
jdct.add(jtf);
if ("替换...".equals(comm)) {
 
 
JLabel jlt = new JLabel(">");
jdct.add(jlt);
jdct.add(jtft);
}
jdct.add(jb);
if ("替换...".equals(comm)) {
JButton jball = new JButton("替换全部");
jball.addActionListener(this);
jdct.add(jball);
}
jdct.pack();
jdct.setResizable(false);
jdct.setLocation(400, 240);
jdct.setVisible(true);
}
if (comm.equals("全选")) {
jta.selectAll();
}
if (comm.equals("关于...")) {
JDialog jdgy = new JDialog(jf, "关于我...");
 
 
jdgy.setLayout(new FlowLayout());
JLabel jl = new JLabel("制作者: xxx ");
JLabel j2 = new JLabel("Email:xxxx@.com ");
jdgy.add(jl);
jdgy.add(j2);
jdgy.setSize(180, 100);
jdgy.setResizable(false);
jdgy.setLocation(400, 240);
jdgy.setVisible(true);
}
//查找实现
if (comm.equals("查找")) {
String str = jtf.getText();
String strall = jta.getText();
int n = strall.indexOf(str, set);
if (n != -1) {
set = n + 1;
jta.setSelectionStart(n);
jta.setSelectionEnd(n + str.length());
}
}
//替换实现
if (comm.equals("替换") || comm.equals("替换全部")) {
al.add(jta.getText());
String str = jtf.getText();
String strall = jta.getText();
if (comm.equals("替换全部")) {
int n1 = 0;
while (true) {
set = strall.indexOf(str, n1);
if (set == -1)
break;
n1 = set + 1;
jta.setSelectionStart(set);
jta.setSelectionEnd(set + str.length());
jta.replaceSelection(jtft.getText());
}
set = 0;
}
int n = strall.indexOf(str, set);
if (n == -1) {
set = 0;
} else {
set = n + 1;
jta.setSelectionStart(n);
jta.setSelectionEnd(n + str.length());
jta.replaceSelection(jtft.getText());
}
}
}
public Notepad() {//构造器
jta.setLineWrap(true);
jta.addMouseListener(this);
JMenuBar jmb = new JMenuBar();
JMenu jm1 = new JMenu("文件");
String[] label1 = { "新建...", "打开...", "保存", "另存...", "退出" };
JMenuItem[] jmi1 = new JMenuItem[label1.length];
for (int i = 0; i < jmi1.length; i++) {
jmi1[i] = new JMenuItem(label1[i]);
jm1.add(jmi1[i]);
jmi1[i].addActionListener(this);
}
jm1.insertSeparator(1);
jm1.insertSeparator(3);
jm1.insertSeparator(6);
JMenu jm2 = new JMenu("编辑");
String[] label2 = { "撤销", "剪切", "复制", "粘贴", "删除", "查找...", "替换...",
"全选" };
JMenuItem[] jmi2 = new JMenuItem[label2.length];
for (int i = 0; i < jmi2.length; i++) {
jmi2[i] = new JMenuItem(label2[i]);
jm2.add(jmi2[i]);
jmi2[i].addActionListener(this);
}
jm2.insertSeparator(1);
jm2.insertSeparator(5);
jm2.insertSeparator(7);
jm2.insertSeparator(10);
JMenu jm3 = new JMenu("帮助");
JMenuItem jmi3 = new JMenuItem("关于...");
jm3.add(jmi3);
jmi3.addActionListener(this);
jmb.add(jm1);
jmb.add(jm2);
jmb.add(jm3);
jf.setJMenuBar(jmb);
jf.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
jf.removeAll();
jf.dispose();
}
});
//鼠标右健弹出菜单
JMenuItem jmi11, jmi22, jmi33, jmi44;
pp.add(jmi11 = new JMenuItem("剪切"));
pp.add(jmi22 = new JMenuItem("复制"));
pp.add(jmi33 = new JMenuItem("粘贴"));
pp.addSeparator();
pp.add(jmi44 = new JMenuItem("全选"));
jmi11.addActionListener(this);
jmi22.addActionListener(this);
jmi33.addActionListener(this);
jmi44.addActionListener(this);
jf.add(pp);
//
//新建菜单
jd.setLayout(new FlowLayout());
JButton jb1 = new JButton("是");
JButton jb2 = new JButton("否");
JButton jb3 = new JButton("取消");
jd.add(new JLabel("您当前编辑未保存,是否保存?"));
jb1.addActionListener(this);
jb2.addActionListener(this);
jb3.addActionListener(this);
jd.add(jb1);
jd.add(jb2);
jd.add(jb3);
jd.pack();
jf.add(jsp);
jf.pack();
jf.setLocation(300, 200);
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new Notepad();
}
public void mouseClicked(MouseEvent e) {
if (e.getButton() == 3) {
pp.setVisible(true);
pp.show(e.getComponent(), e.getX(), e.getY());
}
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
}