王颖奇 20171010129《面向对象程序设计（java）》第十三周学习总结

  实验十三  图形界面事件处理技术

实验时间 2018-11-22

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。

本周理论知识在最后

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：

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)
   {
       //lambda表达式
      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.*;

/**
 * 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);

      // 创建一个带文本的按钮
      JButton yellowButton = new JButton("Yellow");
      JButton blueButton = new JButton("Blue");
      JButton redButton = new JButton("Red");

      buttonPanel = new JPanel();

      // 添加按钮到JPanel中
      buttonPanel.add(yellowButton);
      buttonPanel.add(blueButton);
      buttonPanel.add(redButton);

      // 添加JPanel到框架中
      add(buttonPanel);

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

      // 把操作关联至按钮上
      yellowButton.addActionListener(yellowAction);
      blueButton.addActionListener(blueAction);
      redButton.addActionListener(redAction);
   }

   /**
    * An action listener that sets the panel's background color.
    */
   private class ColorAction implements ActionListener
   //添加事件监听器
   {
      //设置私有属性backgroundColor
      private Color backgroundColor;

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

      public void actionPerformed(ActionEvent event)
      //在事件发生时，调用actionPerformed方法
      {
         buttonPanel.setBackground(backgroundColor);
      }
   }
}

运行结果：

略微简化后的ButtonFrame：

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 buttons to panel
      /*buttonPanel.add(yellowButton);
      buttonPanel.add(blueButton);
      buttonPanel.add(redButton);*/

      // add panel to frame
      add(buttonPanel);

      // create button actions
      /*ColorAction yellowAction = new ColorAction(Color.YELLOW);
      ColorAction blueAction = new ColorAction(Color.BLUE);
      ColorAction redAction = new ColorAction(Color.RED);*/

      // associate actions with buttons
      /*yellowButton.addActionListener(yellowAction);
      blueButton.addActionListener(blueAction);
      redButton.addActionListener(redAction);*/
      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);
   ColorAction action=new ColorAction(backgroundColor);
   button.addActionListener(action);
   }
   /**
    * 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);
      }
   }
}

lambda表达式简化后的ButtonFrame：

package demo;

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) {
        // create buttons
        JButton button = new JButton(name);
        // add buttons to panel
        buttonPanel.add(button);
        // create button actions
        //方法一：通过内部类方式实现
        /*ColorAction action = new ColorAction(backgound);
        // associate actions with buttons
        button.addActionListener(action);*/
        //方法二：匿名内部类方式实现
        /*button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                buttonPanel.setBackground(background);
            }
        });*/
        //方法三通过lambda表达式实现
        button.addActionListener((e)->{
            buttonPanel.setBackground(backgound);
        });
        
    }

    /**
     * An action listener that sets the panel's background color.
     */
    //这是实现了 ActionListener接口的内部类
    /*private class ColorAction implements ActionListener {
        private Color backgroundColor;

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

        public void actionPerformed(ActionEvent event) {
            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 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;

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

   public PlafFrame()
   {
      buttonPanel = new JPanel();
      //UIManager管理组件观感
      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)
   {
      // 添加按钮至Panel

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

      // 建立按钮操作

      button.addActionListener(event -> {
         // 按钮操作: 选择一个新的外观
         try
         {
            UIManager.setLookAndFeel(className);
            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 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.*;

/**
 * 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);

      // add buttons for these actions
      buttonPanel.add(new JButton(yellowAction));
      buttonPanel.add(new JButton(blueAction));
      buttonPanel.add(new JButton(redAction));

      // add panel to frame
      add(buttonPanel);

      // associate the Y, B, and R keys with names
      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");

      // associate the names with actions
      ActionMap amap = buttonPanel.getActionMap();
      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)
      {
         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);
      }
   }
}

运行结果：

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。

代码：

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.*;

/**
 * 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();
         }
      }
   }   
}

运行结果：

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。

代码（本人编写，无法实现停止点名）：

package demo;

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("随机点名器");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);
        });
    }
}

 

package demo;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.Timer;
import java.util.TimerTask;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/**
 * A frame with a button panel
 * 
 * @param <SheThread>
 */
public class ButtonFrame extends JFrame {
    private static ArrayList<String> studentlist;
    private JPanel buttonPanel;
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 200;
    private static volatile boolean flag = false;

    public ButtonFrame() {
        try {
            String temp = null;
            studentlist = new ArrayList<String>();
            File file = new File("C:\\Users\\ASUS\\Desktop\\studentnamelist.txt");
            FileInputStream fis = new FileInputStream(file);
            BufferedReader in = new BufferedReader(new InputStreamReader(fis));
            while ((temp = in.readLine()) != null) {
                Scanner linescanner = new Scanner(temp);
                linescanner.useDelimiter(" ");
                studentlist.add(temp);
            }
            String[] arr = (String[]) studentlist.toArray(new String[studentlist.size()]);
            setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

            buttonPanel = new JPanel();
            buttonPanel.setLayout(null);
            JLabel jLabel = new JLabel("随机点名器");
            JButton jButton = new JButton("点名");
            JButton jbutton = new JButton("点名");
            jLabel.setBounds(130, 40, 200, 30);
            jButton.setBounds(110, 90, 60, 30);
            buttonPanel.setBackground(Color.GREEN);
            jButton.setBackground(Color.RED);

            jButton.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    Timer timer = new Timer();
                    TimerTask timerTask = new TimerTask() {
                        public void run() {
                            String[] name = arr;
                            jLabel.setText(name[(int) Math.round(Math.random() * 42)]);
                        }
                    };
                    timer.schedule(timerTask, 0, 500);
                }
            });

            buttonPanel.add(jLabel);
            buttonPanel.add(jButton);
            add(buttonPanel);

        } catch (FileNotFoundException e) {
            System.out.println("学生信息文件找不到");
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("学生信息文件读取错误");
            e.printStackTrace();
        }

    }
}

运行结果：

示例代码（学长提供）：

package demo;

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);
      
        jla = new JLabel("姓名");
        jlb = new JLabel("准备中");
        jba = new JButton("开始");
        this.add(jla);
        this.add(jlb);
        jla.setFont(new Font("Courier",Font.PLAIN,22));
        jla.setHorizontalAlignment(JLabel.CENTER);
         jla.setVerticalAlignment(JLabel.CENTER);        
         jla.setBounds(20,100,180,30);
         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(150,100,120,30);
          
         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("C:\\Users\\ASUS\\Desktop\\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.MAGENTA);
            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.WHITE);
            jlb.setBackground(Color.gray);
        }
     }
    public static void main(String arguments []){ 
        new NameFrame();
    }
}

由于本人未学习有关JAVA多线程的知识，无法实现线程的停止。

在查阅资料的过程中，本链接中的随机点名方法不太了解：

https://blog.csdn.net/qq_39694972/article/details/83243673

此部分：

 

运行结果：

学习总结：

11.1 事件处理基础
11.2 动作
11.3 鼠标事件
11.4 AWT事件继承层次

 

⚫ 事件源（event source）：能够产生事件的对象都可

以成为事件源，如文本框、按钮等。一个事件源是一个能够注册监听器并向监听器发送事件对象的对象。

⚫ 事件监听器（event listener）：事件监听器对象接收事件源发送的通告（事件对象），并对发生的事件作出响应。一个监听器对象就是一个实现了专门监听器接口的类实例，该类必须实现接口中的方法，这些方法当事件发生时,被自动执行。

⚫ 事件对象（event object）：Java将事件的相关信息封装在一个事件对象中，所有的事件对象都最终派生于java.util.EventObject类。不同的事件源可以产生不同类别的事件。

AWT事件处理机制的概要：

⚫ 监听器对象:是一个实现了特定监听器接口（listener interface）的类实例。

⚫ 事件源:是一个能够注册监听器对象并发送事件对象的对象。

⚫ 当事件发生时，事件源将事件对象自动传递给所有注册的监听器。

⚫ 监听器对象利用事件对象中的信息决定如何对事件做出响应。

GUI设计中，程序员需要对组件的某种事件进行响应和处理时，必须完成两个步骤：

1) 定义实现某事件监听器接口的事件监听器类，并具体化接口中声明的事件处理抽象方法。

2) 为组件注册实现了规定接口的事件监听器对象；

动作事件（ActionEvent）:当特定组件动作（点击按钮）发生时，该组件生成此动作事件。

⚫ 该 事 件 被 传 递 给 组 件 注 册 的 每 一 个ActionListener 对 象 ， 并 调 用 监 听 器 对 象 的actionPerformed方法以接收这类事件对象。

⚫ 能够触发动作事件的动作，主要包括：

(1) 点击按钮

(2) 双击一个列表中的选项；

(3) 选择菜单项；

监听器类必须实现与事件源相对应的接口，即必须提供接口中方法的实现。

 学习感受：

这个周的结对编程练习，由于未学习JAVA多线程的知识，无法完全实现编程题的内容（随机点名器不能停止），深感自己知识的不够。在我查阅资料的过程中，有些看不懂中断线程的两种方法：stop()和interrupt()方法。