Java GUI程序示例

与命令行界面相比，图形界面对于用户来说更为简便易用。图形用户界面（Graphical User Interface，简称 GUI），关于Java图形用户界面，可参见 https://blog.csdn.net/cnds123/article/details/113251233

下面给出几个具体的示例，包括一、 Java猜数字游戏GUI版；二、 JAVA简单画图程序；三、GUI界面人机猜拳小程序；四、简单记事本。源码参考自网络。

一、 Java猜数字游戏GUI版

源码如下：

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants;import java.awt.Dimension;
import java.awt.Font;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;public class GuessNumberGUI extends JFrame{private JTextField txtGuess;private JLabel lblOutput;private JButton btnGuess;private JButton btnPlayAgain;private int theNumber;private int numberOfGames;public void checkGuess() {String guessText = txtGuess.getText();String message = "";try {int guess = Integer.parseInt(guessText);if(guess < theNumber) {message = guess + "小了！再猜！还剩" + (numberOfGames-1) + "次机会！";}else if( guess > theNumber) {message = guess + "大了！再猜！还剩" + (numberOfGames-1) + "次机会！";}else {message = guess + "猜对啦！再玩儿一次";btnPlayAgain.setVisible(true);gameOver();return;}numberOfGames--;if (numberOfGames <= 0){message = guess + "不太好，没有机会了，正确答案是：" + theNumber;btnPlayAgain.setVisible(true);gameOver();}} catch (Exception e) {message = "请输入1-100之间的整数！还剩" + numberOfGames + "次机会！";} finally {lblOutput.setText(message);txtGuess.requestFocus();txtGuess.selectAll();}}public void newGame() {theNumber = (int)(Math.random() * 100 + 1);numberOfGames = 7;  //第一次执行了一次初始化值为6btnGuess.setEnabled(true);txtGuess.setEnabled(true);}//游戏结束使猜测按钮和输入框不可选中public void gameOver(){btnGuess.setEnabled(false);txtGuess.setEnabled(false);}public GuessNumberGUI() {setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setTitle("JAVA猜数字小游戏");getContentPane().setLayout(null);JLabel lblNewLabel = new JLabel("JAVA猜数字");lblNewLabel.setFont(new Font("宋体", Font.BOLD, 15));lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);lblNewLabel.setBounds(159, 27, 116, 18);getContentPane().add(lblNewLabel);JLabel lblNewLabel_1 = new JLabel("输入数字范围1-100");lblNewLabel_1.setHorizontalAlignment(SwingConstants.RIGHT);lblNewLabel_1.setBounds(26, 72, 213, 15);getContentPane().add(lblNewLabel_1);txtGuess = new JTextField();txtGuess.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent arg0) {checkGuess();}});txtGuess.setBounds(250, 69, 66, 21);getContentPane().add(txtGuess);txtGuess.setColumns(10);btnGuess = new JButton("猜一下！");btnGuess.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent arg0) {checkGuess();}});btnGuess.setBounds(170, 114, 93, 23);getContentPane().add(btnGuess);lblOutput = new JLabel("请在上面输入框中输入数字并点击猜一下！现在你有7次机会");lblOutput.setHorizontalAlignment(SwingConstants.CENTER);lblOutput.setBounds(50, 214, 350, 15);getContentPane().add(lblOutput);btnPlayAgain = new JButton("再玩一次！");btnPlayAgain.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {newGame();txtGuess.setText("");lblOutput.setText("请在上面输入框中输入数字并点击猜一下！你有7次机会！");btnPlayAgain.setVisible(false);}});btnPlayAgain.setBounds(164, 164, 105, 23);btnPlayAgain.setVisible(false);getContentPane().add(btnPlayAgain);}public static void main(String args[]) {GuessNumberGUI theGame = new GuessNumberGUI();theGame.newGame();theGame.setSize(new Dimension(450, 300));theGame.setVisible(true);}
}

保存文件名GuessNumberGUI.java（我的保存位置D:\JavaTest）

注意 ：文件名中点后面的后缀（扩展名）不要错了。用记事本写java源码，如果代码中含有中文字符，编码选用ANSI，否则编译通不过，提示 “错误: 编码 GBK 的不可映射字符”。

编译运行参见下图：

​

二、 JAVA简单画图程序

此程序由三个文件组成：Draw.java、Paint.java和DrawListener.java，我将它们都保存于D:\JavaTest。

Draw.java源码如下：

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.BasicStroke;
import javax.swing.JButton;
import javax.swing.JFrame;public class Draw extends JFrame{public static void main(String[] args) {//在主函数中，实例化Draw类的对象，调用初始化界面的方法Draw draw = new Draw();draw.Ondraw();}private Paint[] array = new Paint[100000];//定义存储图形的数组private int x1, y1, x2, y2;//重写父类的重绘方法public void paint (Graphics g) {super.paint(g);Graphics2D g2d = (Graphics2D) g;g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);// 设置画笔抗锯齿//把存储在数组中的图形数据取出来，重新画一次for (int i=0;i<array.length;i++) {Paint p = array[i];//获取数组中指定下标位置的图形对象if(p!=null) {x1=p.getX1();x2=p.getX2();y1=p.getY1();y2=p.getY2();g.setColor(p.getColor());if(p.getName().equals("直线")) {g.drawLine(x1, y1, x2, y2);	} else if(p.getName().equals("矩形")) {g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1-x2),Math.abs(y1-y2));} else if(p.getName().equals("圆")) {g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1-x2),Math.abs(y1-y2));} else if(p.getName().equals("文字")) {g.drawString("这是文字效果", x1, y1);} else if(p.getName().equals("铅笔")||p.getName().equals("刷子")||p.getName().equals("橡皮")) {g2d.setStroke(new BasicStroke(p.getWidth()));g2d.drawLine(x1, y1, x2, y2);} else if(p.getName().equals("喷枪")) {g.drawLine(x1,y1,x2,y2);	} else if(p.getName().equals("长方体")) {int a,b,c,d;a=Math.min(x1, x2);b=Math.max(x1, x2);c=Math.min(y1, y2);d=Math.max(y1, y2);int m=(int)((b-a)*Math.cos(Math.PI/4)*Math.sin(Math.PI/4));int n=(int)((b-a)*Math.cos(Math.PI/4)*Math.sin(Math.PI/4));g.setColor(new Color(100, 200, 100));g.fillRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1-x2),Math.abs(y1-y2));g.setColor(Color.green);g.fillPolygon(new int[] {a, a+m, b+m,b},new int[] {c,c-n,c-n,c},4);g.setColor(Color.black);g.fillPolygon(new int[] {b, b, b+m,b+m},new int[] {c,d,d-n,c-n},4);}elsebreak;}}}public void Ondraw() {//在初始化界面的方法中，实例化JFrame窗体容器组件类的对象//JFrame frame = new JFrame();//设置窗体容器组件对象的属性值：标题、大小、显示位置、关闭操作、可见。this.setTitle("画板");this.setSize(700,700);this.setDefaultCloseOperation(3);this.setLocationRelativeTo(null);//实例化FlowLayout流式布局类的对象，设置对齐方式FlowLayout fl = new FlowLayout(FlowLayout.CENTER);this.setLayout(fl);//在实例化DrawListener类的对象时将获取的画笔对象传递过去DrawListener dl = new DrawListener(this,array);String[] typeArray = {"直线","矩形","圆","文字","铅笔","刷子","橡皮","喷枪","长方体"};for(int i=0;i<typeArray.length;i++) {JButton button = new JButton(typeArray[i]);button.setPreferredSize(new Dimension(80,30));this.add(button);button.addActionListener(dl);//添加动作监听方法}Color[] colorArray = {Color.red,Color.green,Color.blue};for(int i=0;i<colorArray.length;i++) {JButton button = new JButton();button.setBackground(colorArray[i]);button.setPreferredSize(new Dimension(30,30));this.add(button);button.addActionListener(dl);//添加动作监听方法}this.setVisible(true);//获取窗体上的画笔对象Graphics g = this.getGraphics();//给窗体添加鼠标事件监听方法，指定事件的处理类的对象dl;dl.setG(g);//设置方法将画笔g传到DrawListenerthis.addMouseListener(dl);	this.addMouseMotionListener(dl);}
}

Paint.java源码如下：

import java.awt.Color;public class Paint {private int x1,y1,x2,y2;private Color color;private String name;private int width;//线条粗细public Paint(int x1, int y1, int x2, int y2, Color color, String name) {super();this.x1 = x1;this.y1 = y1;this.x2 = x2;this.y2 = y2;this.color = color;this.name = name;}public Paint(int x1, int y1, int x2, int y2, Color color, String name, int width) {super();this.x1 = x1;this.y1 = y1;this.x2 = x2;this.y2 = y2;this.color = color;this.name = name;this.width = width;}//可以把方法写在这里，在Draw类和DrawLisyener类中调用public int getX1() {return x1;}public void setX1(int x1) {this.x1 = x1;}public int getY1() {return y1;}public void setY1(int y1) {this.y1 = y1;}public int getX2() {return x2;}public void setX2(int x2) {this.x2 = x2;}public int getY2() {return y2;}public void setY2(int y2) {this.y2 = y2;}public Color getColor() {return color;}public void setColor(Color color) {this.color = color;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getWidth() {return width;}public void setWidth(int width) {this.width = width;}
}

DrawListener.java源码如下：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;//定义DrawListener事件处理类，该类继承自MouseListener鼠标事件接口，重写接口中的抽象方法。
public class DrawListener implements MouseListener,MouseMotionListener,ActionListener {private int x1,x2,y1,y2;//定义Graphics画笔类的对象属性名private Graphics2D g;public String name = "直线";private Color color = Color.red;private JFrame frame;private Paint[] array;//定义存储图形的数组private int index = 0;public DrawListener(JFrame frame,Paint[] array) {this.frame = frame;this.array = array;}//定义一个带Graphics参数的构造方法public void setG(Graphics g) {this.g = (Graphics2D) g;this.g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);// 设置画笔开启抗锯齿}public void actionPerformed(ActionEvent e) {System.out.println("点击的按钮是："+e.getActionCommand());if(e.getActionCommand().equals("")) {JButton button = (JButton) e.getSource();//获取事件源对象color = button.getBackground();//获取背景颜色}else {name=e.getActionCommand();//获取按钮信息	}}public void mouseDragged(MouseEvent e){//System.out.println("拖动");x2 = e.getX();y2 = e.getY();switch(name) {case "铅笔":g.setStroke(new BasicStroke(2));//设置线条的粗细g.drawLine(x1, y1, x2, y2);//画曲线Paint paint = new Paint(x1,y1,x2,y2,color,name,2);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = paint;//将数组对象存入到数组中x1 = x2;y1 = y2;	break;case "刷子":g.setStroke(new BasicStroke(10));//设置线条的粗细g.drawLine(x1, y1, x2, y2);//画曲线Paint pain = new Paint(x1,y1,x2,y2,color,name,10);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = pain;//将数组对象存入到数组中x1 = x2;y1 = y2;	break;case "橡皮":color = frame.getContentPane().getBackground();g.setColor(color);g.setStroke(new BasicStroke(50));g.drawLine(x1, y1, x2, y2);//画曲线Paint pai = new Paint(x1,y1,x2,y2,color,name,50);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = pai;//将数组对象存入到数组中x1 = x2;y1 = y2;	break;case "喷枪":Random rand = new Random();for(int i=0;i<10;i++) {int p = rand.nextInt(10);int q = rand.nextInt(10);g.drawLine(x2+p, y2+q, x2+p, y2+q);Paint pa = new Paint(x2+p, y2+q, x2+p, y2+q,color,name);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = pa;//将数组对象存入到数组中}x1 = x2;y1 = y2;break;}	}public void mouseMoved(MouseEvent e) {}public void mouseClicked(MouseEvent e) {//System.out.println("点击");}public void mousePressed(MouseEvent e) {//System.out.println("按下");//在按下和释放的事件处理方法中获取按下和释放的坐标值x1 = e.getX();y1 = e.getY();g.setColor(color);}public void mouseReleased(MouseEvent e) {//System.out.println("释放");x2 = e.getX();y2 = e.getY();//设置画笔的颜色//g.setColor(Color.green);//g.setColor(new Color(100, 100, 100));//根据按下和释放的坐标值，使用Graphics对象进行画图g.setStroke(new BasicStroke(1));//设置线条的粗细switch(name) {case "直线":g.drawLine(x1, y1, x2, y2);Paint paint = new Paint(x1,y1,x2,y2,color,name,1);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = paint;//将图形对象存入到数组中break;case "矩形":g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1-x2),Math.abs(y1-y2));Paint k = new Paint(x1,y1,x2,y2,color,name,1);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = k;//将图形对象存入到数组中break;case "圆":g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1-x2),Math.abs(y1-y2));Paint f = new Paint(x1,y1,x2,y2,color,name,1);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = f;//将图形对象存入到数组中break;case "文字":g.drawString("这是文字效果", x1, y1);Paint j = new Paint(x1,y1,x2,y2,color,name,1);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = j;//将图形对象存入到数组中break;case "长方体":g.setColor(new Color(100, 200, 100));g.fillRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1-x2),Math.abs(y1-y2));int a,b,c,d;a=Math.min(x1, x2);b=Math.max(x1, x2);c=Math.min(y1, y2);d=Math.max(y1, y2);int m=(int)((b-a)*Math.cos(Math.PI/4)*Math.sin(Math.PI/4));int n=(int)((b-a)*Math.cos(Math.PI/4)*Math.sin(Math.PI/4));//顶面g.setColor(Color.green);g.fillPolygon(new int[] {a, a+m, b+m,b},new int[] {c,c-n,c-n,c},4);//右侧面g.setColor(Color.black);g.fillPolygon(new int[] {b, b, b+m,b+m},new int[] {c,d,d-n,c-n},4);Paint h = new Paint(x1,y1,x2,y2,color,name,1);//根据图形的数据实例化Paint对象if(index<1000)array[index++] = h;//将图形对象存入到数组中break;}		}public void mouseEntered(MouseEvent e) {//System.out.println("进入");}public void mouseExited(MouseEvent e) {//System.out.println("离开");}
}

编译运行参见下图：

三、GUI界面人机猜拳小程序

 本程序需要四个图像（我的保存位置D:\JavaTest\image2）

源码如下：

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;public class CaiQuan {public static void main(String[] args) {// 窗口JFrame caiquan = new JFrame("猜拳");caiquan.setSize(700, 550);caiquan.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);caiquan.setLocation(650, 250);JTextField jieguo = new JTextField();JLabel diannao = new JLabel("电脑");JLabel people = new JLabel("人");JLabel tishi = new JLabel("请先选择人要出的内容");JLabel jieguotishi = new JLabel("结果是:");JLabel bijiao = new JLabel();//图片Icon jiandaotu = new ImageIcon("image2\\剪刀.jpg");Icon shitoutu = new ImageIcon("image2\\石头.jpg");Icon butu = new ImageIcon("image2\\布.jpg");Icon kongbai = new ImageIcon("image2\\空白.jpg");// 按钮JButton wanjia = new JButton("玩家");JButton dadiannao = new JButton(kongbai);JButton shitou = new JButton("石头");JButton jiandao = new JButton("剪刀");JButton bu = new JButton("布");JButton caipan = new JButton("裁判");//布局caiquan.setLayout(null);//电脑和人的文本布局tishi.setBounds(270, 0, 150, 60);diannao.setBounds(70, 20, 50, 50);people.setBounds(490, 20, 50, 50);//结果提示框jieguo.setBounds(295, 420, 80, 20);jieguotishi.setBounds(250, 420, 100, 20);//电脑和玩家大按钮布局dadiannao.setBounds(30, 70, 300, 300);wanjia.setBounds(360, 70, 300, 300);// 石头剪刀布caipan 按钮布局shitou.setBounds(420, 400, 60, 40);jiandao.setBounds(480, 400, 60, 40);bu.setBounds(540, 400, 60, 40);caipan.setBounds(100, 400, 80, 40);
//        最上边提示布局caiquan.add(tishi);
//        电脑和玩家文本提示caiquan.add(diannao);caiquan.add(people);
//        电脑和玩家按钮caiquan.add(dadiannao);caiquan.add(wanjia);
//        石头剪刀布caipan按钮caiquan.add(caipan);caiquan.add(shitou);caiquan.add(jiandao);caiquan.add(bu);caiquan.setVisible(true);// 添加响应
//电脑随机class MyAction implements ActionListener {@Overridepublic void actionPerformed(ActionEvent e) {int suiji = (int) (Math.random() * 3 + 1);String a = bijiao.getText();if (suiji == 1) {dadiannao.setIcon(jiandaotu);if (a.equals("jiandao")) {JOptionPane.showMessageDialog(null, "平局", "结果", JOptionPane.ERROR_MESSAGE);} else if (a.equals("shitou")) {JOptionPane.showMessageDialog(null, "人赢了", "结果", JOptionPane.ERROR_MESSAGE);} else if (a.equals("bu")) {JOptionPane.showMessageDialog(null, "电脑赢了", "结果", JOptionPane.ERROR_MESSAGE);}}if (suiji == 2) {dadiannao.setIcon(shitoutu);if (a.equals("shitou")) {JOptionPane.showMessageDialog(null, "平局", "结果", JOptionPane.ERROR_MESSAGE);} else if (a.equals("bu")) {JOptionPane.showMessageDialog(null, "人赢了", "结果", JOptionPane.ERROR_MESSAGE);} else if (a.equals("jiandao")) {JOptionPane.showMessageDialog(null, "电脑赢了", "结果", JOptionPane.ERROR_MESSAGE);}}if (suiji == 3) {dadiannao.setIcon(butu);if (a.equals("bu")) {JOptionPane.showMessageDialog(null, "平局", "结果", JOptionPane.ERROR_MESSAGE);} else if (a.equals("jiandao")) {JOptionPane.showMessageDialog(null, "人赢了", "结果", JOptionPane.ERROR_MESSAGE);} else if (a.equals("shitou")) {JOptionPane.showMessageDialog(null, "电脑赢了", "结果", JOptionPane.ERROR_MESSAGE);}}}}
// 人选择class PeopleChoose implements ActionListener {@Overridepublic void actionPerformed(ActionEvent b) {if (b.getSource() == jiandao) {wanjia.setIcon(jiandaotu);bijiao.setText("jiandao");} else if (b.getSource() == shitou) {wanjia.setIcon(shitoutu);bijiao.setText("shitou");} else if (b.getSource() == bu) {wanjia.setIcon(butu);bijiao.setText("bu");}}}//        电脑随机监听MyAction m1 = new MyAction();caipan.addActionListener(m1);//        人选择监听PeopleChoose p1 = new PeopleChoose();jiandao.addActionListener(p1);shitou.addActionListener(p1);bu.addActionListener(p1);}
}

保存文件名CaiQuan.java（我的保存位置D:\JavaTest）

编译运行参见下图：

四、简单记事本

本程序需要一个图像做标题栏图标（我的保存位置D:\JavaTest2\image2）

 此程序由两个文件组成：Draw.java、和DrawListener.java，我将它们都保存于D:\JavaTest2。

NotepadMain.java源码如下：

public class NotepadMain {public static void main(String[] str) {MyNotePad notePad = new MyNotePad();}
}

MyNotePad.java源码如下： 

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter; //
class MyNotePad extends JFrame implements ActionListener {private JTextArea jta = null;private JMenuBar jmb = null;private JMenu jm = null;private JMenuItem jmiOpen = null;private JMenuItem jmiSave = null;private JMenuItem jmiExit = null;private JFileChooser jfc = null;public MyNotePad() {// 设置窗口 iconImage icon = Toolkit.getDefaultToolkit().getImage("image/icon1.png");this.setIconImage(icon);jta = new JTextArea();this.setLayout(new BorderLayout());this.add(jta);jmb = new JMenuBar();jm = new JMenu("文件");jmiOpen = new JMenuItem("打开");jmiOpen.addActionListener(this);jmiOpen.setActionCommand("打开");jmiSave = new JMenuItem("保存");jmiSave.addActionListener(this);jmiSave.setActionCommand("保存");jmiExit = new JMenuItem("退出");jmiExit.addActionListener(this);jmiExit.setActionCommand("退出");jm.add(jmiOpen);jm.add(jmiSave);jm.add(jmiExit);jmb.add(jm);this.setJMenuBar(jmb);this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);this.setSize(400, 300);this.setVisible(true);}@Overridepublic void actionPerformed(ActionEvent e) {// TODO Auto-generated method stubString str = e.getActionCommand();if (str.equals("打开")) {System.out.println("打开");jfc = new JFileChooser();FileNameExtensionFilter filter = new FileNameExtensionFilter("txt文件","txt");// 创建文件类型过滤器jfc.setFileFilter(filter);// 设置选择器的过滤器jfc.setDialogTitle("请选择文件！");jfc.showOpenDialog(null);jfc.setVisible(true);File file = jfc.getSelectedFile();BufferedReader br = null;try {//FileReader fReader = new FileReader(file); //默认编码ANSIInputStreamReader fReader =new InputStreamReader(new FileInputStream(file), "UTF-8"); //br = new BufferedReader(fReader);String readStr = "";String allCode = "";while ((readStr = br.readLine()) != null) {allCode += readStr + "\r\n";}jta.setText(allCode);} catch (Exception e2) {e2.printStackTrace();// TODO: handle exception} finally {try {br.close();} catch (IOException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}}} else if (str.equals("保存")) {JFileChooser jfc = new JFileChooser();FileNameExtensionFilter filter = new FileNameExtensionFilter("txt文件","txt");// 创建文件类型过滤器jfc.setFileFilter(filter);// 设置选择器的过滤器jfc.setDialogTitle("已保存");jfc.showSaveDialog(null);File file = jfc.getSelectedFile();BufferedWriter bw = null;try {//FileWriter fw = new FileWriter(file); //默认编码ANSIOutputStreamWriter fw = new OutputStreamWriter(new FileOutputStream(file),"utf-8"); //bw = new BufferedWriter(fw);String jtaStr = jta.getText();bw.write(jtaStr);} catch (Exception e2) {// TODO: handle exceptione2.printStackTrace();} finally {try {bw.close();} catch (IOException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}}} else if (str.equals("退出")) {System.exit(0);}}
}

编译运行参见下图：