201771010112罗松《面向对象程序设计（java）》第十三周学习总结

一、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。

二、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。

package 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");// 将窗体的标题设置为指定的字符串。
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);// 设置用户在窗体上发起 "close" 时默认执行的操作。
            frame.setVisible(true);// 设置窗口可见
        });
    }
}

package button;

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;
    private static final int DEFAULT_HEIGHT = 200;

    public ButtonFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);// 调整组件的大小.

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

        buttonPanel = new JPanel();

        // 将按钮添加到面板中
        buttonPanel.add(yellowButton);
        buttonPanel.add(blueButton);
        buttonPanel.add(redButton);

        add(buttonPanel);

        // 为每种颜色创建一个对象
        ColorAction yellowAction = new ColorAction(Color.YELLOW);
        ColorAction blueAction = new ColorAction(Color.BLUE);
        ColorAction redAction = new ColorAction(Color.RED);

        // 将这些对象设置为按钮监听器
        yellowButton.addActionListener(yellowAction);
        blueButton.addActionListener(blueAction);
        redButton.addActionListener(redAction);
    }

    /**
     * An action listener that sets the panel's background color.
     */
    private class ColorAction implements ActionListener {
        private Color backgroundColor;

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

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

匿名类简化：

package button;

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;
    private static final int DEFAULT_HEIGHT = 200;

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

        buttonPanel = new JPanel();
        add(buttonPanel);

        makeButton("Yellow", Color.yellow);
        makeButton("blue", Color.blue);
        makeButton("red", Color.red);
    }

    public void makeButton(String name, Color backgroundColor) {
        JButton button = new JButton(name);
        buttonPanel.add(button);
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                buttonPanel.setBackground(backgroundColor);
            }
        });
    }
}

lambda表达式简化：

package button;

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;
    private static final int DEFAULT_HEIGHT = 200;

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

        buttonPanel = new JPanel();

        add(buttonPanel);

        makeButton("黄色", Color.yellow);
        makeButton("蓝色", Color.blue);
        makeButton("红色", Color.red);
    }

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

    }

}

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。

代码：

package Second;

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 Second;

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

/**
 * A frame with a button panel for changing look-and-feel
 */
public class PlafFrame extends JFrame
{
   private JPanel buttonPanel;

   public PlafFrame()
   {
      buttonPanel = new JPanel();
      //获取所有安装的观感实现

      UIManager.LookAndFeelInfo[] infos = UIManager.getInstalledLookAndFeels();
      for (UIManager.LookAndFeelInfo info : infos)
         makeButton(info.getName(), info.getClassName());

      add(buttonPanel);
      pack();
   }

   /**
    * Makes a button to change the pluggable look-and-feel.
    * @param name the button name
    * @param className the name of the look-and-feel class
    */
   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);
            //调用静态方法，刷新全部的组件集。这里需要向方法提供一个组件，并由此找到其他的所有组件
            //外部对象的this引用必须将外部类名作为前缀

            SwingUtilities.updateComponentTreeUI(this);
            pack();
         }
         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；

掌握GUI程序中按钮、键盘动作映射到动作对象的方法。

代码：

package three;

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 three;

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

/**
 * A frame with a panel that demonstrates color change actions.
 */
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();

      // define actions
      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);

    //用Action对象构造按钮，把动作和按钮关联起来

      buttonPanel.add(new JButton(yellowAction));
      buttonPanel.add(new JButton(blueAction));
      buttonPanel.add(new JButton(redAction));

      // add panel to frame
      add(buttonPanel);
     
    //得到顶层组件的WHEN_ANCESTOR_OF_FOCUSED_COMPONENT输入映射

      // associate the Y, B, and R keys with names
      InputMap imap = buttonPanel.getInputMap(JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
     //将(按键，动作键)添加到输入映射中
      imap.put(KeyStroke.getKeyStroke("ctrl Y"), "panel.yellow");
      imap.put(KeyStroke.getKeyStroke("ctrl B"), "panel.blue");
      imap.put(KeyStroke.getKeyStroke("ctrl R"), "panel.red");

      // associate the names with actions、
      //得到顶层组件的动作映射
      ActionMap amap = buttonPanel.getActionMap();
    //将(动作键，动作对象)添加到映射中

      amap.put("panel.yellow", yellowAction);
      amap.put("panel.blue", blueAction);
      amap.put("panel.red", redAction);
   }
   
   public class ColorAction extends AbstractAction
   {
      /**
       * Constructs a color action.
       * @param name the name to show on the button
       * @param icon the icon to display on the button
       * @param c the background color
       */
      public ColorAction(String name, Icon icon, Color c)
      {
        //存储命令的名称、图标、简要说明和需要的颜色
         putValue(Action.NAME, name);
         putValue(Action.SMALL_ICON, icon);
         putValue(Action.SHORT_DESCRIPTION, "Set panel color to " + name.toLowerCase());//显示在工具提示里

         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);
      });
   }
}

MouseTest

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();
   }
}

MouseFrame

package mouse;

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

/**
 * A component with mouse operations for adding and removing squares.
 */
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; // the square containing the mouse cursor

   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;

      // draw all squares
      for (Rectangle2D r : squares)
         g2.draw(r);
   }

   /**
    * Finds the first square containing a point.
    * @param p a point
    * @return the first square that contains p
    */
   public Rectangle2D find(Point2D p)
   {
      for (Rectangle2D r : squares)
      {
         if (r.contains(p)) return r;
      }
      return null;
   }

   /**
    * Adds a square to the collection.
    * @param p the center of the square
    */
   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();
   }

   /**
    * Removes a square from the collection.
    * @param s the square to remove
    */
   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)
      {
         // add a new square if the cursor isn't inside a square
         current = find(event.getPoint());
         if (current == null) add(event.getPoint());
      }

      public void mouseClicked(MouseEvent event)
      {
         // remove the current square if double clicked
         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
         // a rectangle

         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();

            // drag the current rectangle to center it at (x, y)
            current.setFrame(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH);
            repaint();
         }
      }
   }   
}

MouseComponent

 

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

package 点名器;

import java.awt.EventQueue;
import javax.swing.JFrame;

public class test {
    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            ButtonFrame frame = new ButtonFrame();
            frame.setTitle("点名器");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);
            frame.setResizable(false);
        });
    }
}

package 点名器;

import java.awt.Color;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import java.util.Timer;

import javax.swing.*;

public class ButtonFrame extends JFrame {
    JButton pausecontBtn;
    private ArrayList arrayList;

    {
        arrayList = new ArrayList<>();
        File file = new File("studentnamelist.txt");
        FileInputStream fis;
        try {
            fis = new FileInputStream(file);
            InputStreamReader in = new InputStreamReader(fis);
            BufferedReader bf = new BufferedReader(in);
            String readLine;
            while ((readLine = bf.readLine()) != null) {
                arrayList.add(readLine);
            }
        } catch (FileNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
    }
    private JPanel buttonPanel;
    private static final int DEFAULT_WIDTH = 500;
    private static final int DEFAULT_HEIGHT = 300;
    protected static final String ture = null;

    public ButtonFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
        buttonPanel = new JPanel();
        buttonPanel.setLayout(null);
        JLabel jLabel = new JLabel("随机点名器");
        JButton jButton = new JButton("开始");
        jLabel.setBounds(200, 40, 65, 40);
        jButton.setBounds(200, 90, 65, 40);
        jButton.addActionListener(new ActionListener() {
            Timer timer;

            public void actionPerformed(ActionEvent e) {
                if (jButton.getText().equals("开始")) {
                    timer = new Timer();
                    TimerTask timerTask = new TimerTask() {
                        public void run() {
                            jButton.setText("停止");
                            jButton.setBackground(Color.yellow);
                            jLabel.setText((String) arrayList.get((int) (Math.random() * 42)));
                        }
                    };
                    timer.schedule(timerTask, 0, 5);
                }
                if (jButton.getText().equals("停止")) {
                    timer.cancel();
                    jButton.setText("开始");
                    jButton.setBackground(Color.red);
                }
            }
        });
        buttonPanel.add(jLabel);
        buttonPanel.add(jButton);
        add(buttonPanel);
    }
}

三、实验总结：

通过这次实验我了解了事件处理的基本原理，知道了它的用途，了解了AWT事件模型的工作机制，事件处理的基本编程模型，还了解了GUI界面组件观感设置方法，掌握了WindowAdapter类、AbstractAction类的用法以及GUI程序中鼠标事件处理技术。并且在这次实验中通过结对编程知道了如何去互相学习，收获很大。