李清华201772020113《面向对象程序设计（java）》第十三周学习总结

1、实验目的与要求

(1) 掌握事件处理的基本原理，理解其用途；

(2) 掌握AWT事件模型的工作机制；

(3) 掌握事件处理的基本编程模型；

(4) 了解GUI界面组件观感设置方法；

(5) 掌握WindowAdapter类、AbstractAction类的用法；

(6) 掌握GUI程序中鼠标事件处理技术。

2、实验内容和步骤

实验1： 导入第11章示例程序，测试程序并进行代码注释。

测试程序1：

l  在elipse IDE中调试运行教材443页-444页程序11-1，结合程序运行结果理解程序；

l  在事件处理相关代码处添加注释；

l  用lambda表达式简化程序；

l  掌握JButton组件的基本API；

l  掌握Java中事件处理的基本编程模型。

代码：

 ackage button;

 import java.awt.*;
 import javax.swing.*;

 /**
  * @version 1.34 2015-06-12
  * @author Cay Horstmann
  */
 public class ButtonTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          JFrame frame = new ButtonFrame();
          frame.setTitle("ButtonTest");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 package button;

 import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;

 /**
  * 带按钮面板的框架
  */
 public class ButtonFrame extends JFrame
 {
    private JPanel buttonPanel;
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 200;

    public ButtonFrame()
    {
       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

       // 创建按钮
       JButton yellowButton = new JButton("Yellow");
       JButton blueButton = new JButton("Blue");
       JButton redButton = new JButton("Red");

       buttonPanel = new JPanel();

       // 向面板添加按钮
       buttonPanel.add(yellowButton);
       buttonPanel.add(blueButton);
       buttonPanel.add(redButton);

       // 将面板添加到帧
       add(buttonPanel);

       // 创建按钮动作
       ColorAction yellowAction = new ColorAction(Color.YELLOW);
       ColorAction blueAction = new ColorAction(Color.BLUE);
       ColorAction redAction = new ColorAction(Color.RED);

       // 用按钮关联动作
       yellowButton.addActionListener(yellowAction);
       blueButton.addActionListener(blueAction);
       redButton.addActionListener(redAction);
    }

    /**
     * 设置面板背景颜色的ActualListInter.
     */
    private class ColorAction implements ActionListener
    {
       private Color backgroundColor;

       public ColorAction(Color c)
       {
          backgroundColor = c;
       }

       public void actionPerformed(ActionEvent event)
       {
          buttonPanel.setBackground(backgroundColor);
       }
    }
 }

用lambda表达式简化后：

代码：

 package lambda;

 import java.awt.*;
 import javax.swing.*;

 /**
  * @version 1.34 2015-06-12
  * @author Cay Horstmann
  */
 public class ButtonTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          JFrame frame = new ButtonFrame();
          frame.setTitle("ButtonTest");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 package lambda;

 import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;

 /**
  * A frame with a button panel
  */
 public class ButtonFrame extends JFrame {
     private JPanel buttonPanel;
     private static final int DEFAULT_WIDTH = 300 * 2;
     private static final int DEFAULT_HEIGHT = 200 * 2;

     public ButtonFrame() {
         setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
         buttonPanel = new JPanel();
         makeButton("黄色", Color.yellow);
         makeButton("蓝色", Color.blue);
         makeButton("红色", Color.red);
         makeButton("绿色", Color.green);
         add(buttonPanel);

     }

     protected void makeButton(String name, Color backgound) {
         JButton button = new JButton(name);
         buttonPanel.add(button);
         button.addActionListener((e) -> {
             buttonPanel.setBackground(backgound);
         });
     }
 }

实验结果：

测试程序2：

l  在elipse IDE中调试运行教材449页程序11-2，结合程序运行结果理解程序；

l  在组件观感设置代码处添加注释；

l  了解GUI程序中观感的设置方法。

 package plaf;

 import java.awt.*;
 import javax.swing.*;

 /**
  * @version 1.32 2015-06-12
  * @author Cay Horstmann
  */
 public class PlafTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          JFrame frame = new PlafFrame();
          frame.setTitle("PlafTest");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 package plaf;

 import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JPanel;
 import javax.swing.SwingUtilities;
 import javax.swing.UIManager;

 /**
  * 带有按钮面板的框架，用于改变外观和感觉
  */
 public class PlafFrame extends JFrame
 {
    private JPanel buttonPanel;

    public PlafFrame()
    {
       buttonPanel = new JPanel();

       UIManager.LookAndFeelInfo[] infos = UIManager.getInstalledLookAndFeels();//获取所有的显示样式
       for (UIManager.LookAndFeelInfo info : infos)
          makeButton(info.getName(), info.getClassName());

       add(buttonPanel);//增加按钮点击事件
       pack();
    }

    /**
     * 制作一个按钮来改变可插入的外观和感觉
     * @param 命名按钮名称
     * @param 类名：外观类的名称
     */
    private void makeButton(String name, String className)
    {
       // 向面板添加按钮

       JButton button = new JButton(name);
       buttonPanel.add(button);

       // 设置按钮动作

       button.addActionListener(event -> {
          // 按钮动作：切换到新的外观和感觉
          try
          {
             UIManager.setLookAndFeel(className);//设置外观的显示方式
             SwingUtilities.updateComponentTreeUI(this);//给定一个组件后，更新所有的组件。
             pack();//依据放置的组件设定窗口的大小，使之正好能容纳放置的所有组件
          }
          catch (Exception e)
          {
             e.printStackTrace();
          }
       });
    }
 }

测试程序3：

l  在elipse IDE中调试运行教材457页-458页程序11-3，结合程序运行结果理解程序；

l  掌握AbstractAction类及其动作对象；

l  掌握GUI程序中按钮、键盘动作映射到动作对象的方法。

 package action;

 import java.awt.*;
 import javax.swing.*;

 /**
  * @version 1.34 2015-06-12
  * @author Cay Horstmann
  */
 public class ActionTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          JFrame frame = new ActionFrame();
          frame.setTitle("ActionTest");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 package action;

 import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;

 /**
  * 具有显示颜色变化动作的面板的框架
  */
 public class ActionFrame extends JFrame
 {
    private JPanel buttonPanel;
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 200;

    public ActionFrame()
    {
       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

       buttonPanel = new JPanel();

       // 定义行为
       Action yellowAction = new ColorAction("Yellow", new ImageIcon("yellow-ball.gif"),
             Color.YELLOW);
       Action blueAction = new ColorAction("Blue", new ImageIcon("blue-ball.gif"), Color.BLUE);
       Action redAction = new ColorAction("Red", new ImageIcon("red-ball.gif"), Color.RED);

       // 为这些操作添加按钮
       buttonPanel.add(new JButton(yellowAction));
       buttonPanel.add(new JButton(blueAction));
       buttonPanel.add(new JButton(redAction));

       // 将面板添加到框架
       add(buttonPanel);

       // 将Y、B和R键与名称关联
       InputMap imap = buttonPanel.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
       imap.put(KeyStroke.getKeyStroke("ctrl Y"), "panel.yellow");
       imap.put(KeyStroke.getKeyStroke("ctrl B"), "panel.blue");
       imap.put(KeyStroke.getKeyStroke("ctrl R"), "panel.red");

       // 把名字和动作联系起来
       ActionMap amap = buttonPanel.getActionMap();
       amap.put("panel.yellow", yellowAction);
       amap.put("panel.blue", blueAction);
       amap.put("panel.red", redAction);
    }

    public class ColorAction extends AbstractAction
    {
       /**
        * 构造颜色动作。
        * @param 在按钮上显示要显示的名称
        * @param 图标按钮上显示的图标
        * @param 背景颜色
        */
       public ColorAction(String name, Icon icon, Color c)
       {
          putValue(Action.NAME, name);
          putValue(Action.SMALL_ICON, icon);
          putValue(Action.SHORT_DESCRIPTION, "Set panel color to " + name.toLowerCase());
          putValue("color", c);
       }

       public void actionPerformed(ActionEvent event)
       {
          Color c = (Color) getValue("color");
          buttonPanel.setBackground(c);
       }
    }
 }

测试程序4：

l  在elipse IDE中调试运行教材462页程序11-4、11-5，结合程序运行结果理解程序；

l  掌握GUI程序中鼠标事件处理技术。

 package mouse;

 import java.awt.*;
 import javax.swing.*;

 /**
  * @version 1.34 2015-06-12
  * @author Cay Horstmann
  */
 public class MouseTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          JFrame frame = new MouseFrame();
          frame.setTitle("MouseTest");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 package mouse;

 import javax.swing.*;

 /**
  * A frame containing a panel for testing mouse operations
  */
 public class MouseFrame extends JFrame
 {
    public MouseFrame()
    {
       add(new MouseComponent());
       pack();
    }
 }

 package mouse;

 import java.awt.*;
 import java.awt.event.*;
 import java.awt.geom.*;
 import java.util.*;
 import javax.swing.*;

 /**
  * 一个带有鼠标操作的用于添加和删除正方形的组件
  */
 public class MouseComponent extends JComponent
 {
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 200;

    private static final int SIDELENGTH = 10;
    private ArrayList<Rectangle2D> squares;
    private Rectangle2D current; //包含鼠标光标的正方形

    public MouseComponent()
    {
       squares = new ArrayList<>();
       current = null;

       addMouseListener(new MouseHandler());
       addMouseMotionListener(new MouseMotionHandler());
    }

    public Dimension getPreferredSize() { return new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT); }   

    public void paintComponent(Graphics g)
    {
       Graphics2D g2 = (Graphics2D) g;

       // 绘制所有正方形
       for (Rectangle2D r : squares)
          g2.draw(r);
    }

    /**
     * 找到包含一个点的第一个方块。
     * @param P—A点
     * @return 包含P的第一个正方形
     */
    public Rectangle2D find(Point2D p)
    {
       for (Rectangle2D r : squares)
       {
          if (r.contains(p)) return r;
       }
       return null;
    }

    /**
     * 向集合中添加正方形
     * @param p在正方形的中心
     */
    public void add(Point2D p)
    {
       double x = p.getX();
       double y = p.getY();

       current = new Rectangle2D.Double(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH,
             SIDELENGTH);
       squares.add(current);
       repaint();
    }

    /**
     * 从集合中移除正方形.
     * @param 从正方形中移除s
     */
    public void remove(Rectangle2D s)
    {
       if (s == null) return;
       if (s == current) current = null;
       squares.remove(s);
       repaint();
    }

    private class MouseHandler extends MouseAdapter
    {
       public void mousePressed(MouseEvent event)
       {
          // 如果光标不在正方形中，则添加一个新的正方形
          current = find(event.getPoint());
          if (current == null) add(event.getPoint());
       }

       public void mouseClicked(MouseEvent event)
       {
          // 如果双击，删除当前方块
          current = find(event.getPoint());
          if (current != null && event.getClickCount() >= 2) remove(current);
       }
    }

    private class MouseMotionHandler implements MouseMotionListener
    {
       public void mouseMoved(MouseEvent event)
       {
          // set the mouse cursor to cross hairs if it is inside
          // 一个长方形

          if (find(event.getPoint()) == null) setCursor(Cursor.getDefaultCursor());
          else setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
       }

       public void mouseDragged(MouseEvent event)
       {
          if (current != null)
          {
             int x = event.getX();
             int y = event.getY();

             // 拖动当前矩形将其置于（x，y）中心
             current.setFrame(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH);
             repaint();
          }
       }
    }
 }

实验2：结对编程练习

利用班级名单文件、文本框和按钮组件，设计一个有如下界面（图1）的点名器，要求用户点击开始按钮后在文本输入框随机显示2017级网络与信息安全班同学姓名，如图2所示，点击停止按钮后，文本输入框不再变换同学姓名，此同学则是被点到的同学姓名。

图1 点名器启动界面

图2 点名器点名界面

 package dmq2;

 import java.util.*;
 import java.awt.*;
 import javax.swing.*;
 import java.awt.event.*;
 import java.io.File;
 import java.io.FileNotFoundException;

 import javax.swing.event.*;

 public class NameFrame extends JFrame implements ActionListener {
     //private JLabel jla;
     private JLabel jlb;
     private JButton jba;
     private static boolean flag = true;

     public NameFrame() {
         this.setLayout(null);

         jlb = new JLabel("随机点名器");
         jba = new JButton("开始");
         this.add(jlb);
         jlb.setOpaque(true);
         jlb.setBackground(Color.cyan);
         jlb.setFont(new Font("Courier", Font.PLAIN, 22));
         jlb.setHorizontalAlignment(JLabel.CENTER);
         jlb.setVerticalAlignment(JLabel.CENTER);
         jlb.setBounds(120, 100, 150, 30);

         this.add(jba);
         jba.setBounds(150, 150, 80, 26);

         jba.addActionListener(this);

         this.setTitle("点名器");
         this.setBounds(400, 400, 400, 300);
         this.setVisible(true);
         this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
     }

     public void actionPerformed(ActionEvent e) {
         int i = 0;
         String names[] = new String[50];
         try {
             Scanner in = new Scanner(new File("studentnamelist.txt"));
             while (in.hasNextLine()) {
                 names[i] = in.nextLine();
                 i++;
             }
         } catch (FileNotFoundException e1) {
             // TODO Auto-generated catch block
             e1.printStackTrace();
         }
         if (jba.getText() == "开始") {
             jlb.setBackground(Color.RED);
             flag = true;
             new Thread() {
                 public void run() {
                     while (NameFrame.flag) {
                         Random r = new Random();//
                         int i = r.nextInt(47);
                         jlb.setText(names[i]);
                     }
                 }
             }.start();
             jba.setText("停止");
             jba.setBackground(Color.YELLOW);
         } else if (jba.getText() == "停止") {
             flag = false;
             jba.setText("开始");
             jba.setBackground(Color.RED);
             jlb.setBackground(Color.gray);
         }
     }

     public static void main(String arguments[]) {
         new NameFrame();
     }
 }