201771010142張燕/楊蓉慶實驗十三 圖形界面事件處理技術

實驗十三  圖形界面事件處理技術

實驗時間 2018-11-22

 

基礎知識：

 ⚫ 事件源（event source）：可以產生事件的對象均可 以成爲事件源，如文本框、按鈕等。一個事件源是一個 可以註冊監聽器並向監聽器發送事件對象的對象。

⚫ 事件監聽器（event listener）：事件監聽器對象接 收事件源發送的通告（事件對象），並對發生的事件做 出響應。一個監聽器對象就是一個實現了專門監聽器接 口的類實例，該類必須實現接口中的方法，這些方法當 事件發生時,被自動執行。

⚫ 事件對象（event object）：Java將事件的相關信息 封裝在一個事件對象中，全部的事件對象都最終派生於 java.util.EventObject類。不一樣的事件源能夠產生不 同類別的事件

AWT事件處理機制的概要： ⚫ 監聽器對象:是一個實現了特定監聽器接口（ listener interface）的類實例。

⚫ 事件源:是一個可以註冊監聽器對象併發送事件對 象的對象。

⚫ 當事件發生時，事件源將事件對象自動傳遞給所 有註冊的監聽器。

⚫ 監聽器對象利用事件對象中的信息決定如何對事 件作出響應。

GUI設計中，程序員須要對組件的某種事件進行響應和處理時，必須完成兩個步驟：

1) 定義實現某事件監聽器接口的事件監聽器類，並具體化接口中聲明的事件處理抽象方法。

2) 爲組件註冊實現了規定接口的事件監聽器對象；

⚫ 註冊監聽器方法 eventSourceObject.addEventListener(eventListenerObject)

⚫ 下面是監聽器的一個示例： ActionListener listener = …;

JButton button=new JButton(「Ok」); button.addActionListener(listener);

⚫ 動做事件（ActionEvent）:當特定組件動做（點 擊按鈕）發生時，該組件生成此動做事件。

⚫ 該 事 件 被 傳 遞 給 組 件 注 冊 的 每 一 個 ActionListener 對象， 並 調 用 監 聽 器 對 象 的 actionPerformed方法以接收這類事件對象。

⚫ 可以觸發動做事件的動做，主要包括：

(1) 點擊按鈕

(2) 雙擊一個列表中的選項；

(3) 選擇菜單項；

(4) 在文本框中輸入回車。

11.1.1  監聽器接口的實現

監聽器類必須實現與事件源相對應的接口，即必須提供接口中方法的實現。

⚫ 監聽器接口方法實現 class Mylistener implements ActionListener {  public void actionPerformed (ActionEvent event) {  …… }}

 private class ColorAction implements ActionListener

   {

     public ColorAction(Color c)

   {

      backgroundColor = c;

  }.

  public void actionPerformed(ActionEvent event)

   {

       buttonPanel.setBackground(backgroundColor);

   }.

    private Color backgroundColor;

 }

實驗內容

1、實驗目的與要求

(1) 掌握事件處理的基本原理，理解其用途；

(2) 掌握AWT事件模型的工做機制；

(3) 掌握事件處理的基本編程模型；

(4) 瞭解GUI界面組件觀感設置方法；

(5) 掌握WindowAdapter類、AbstractAction類的用法；

(6) 掌握GUI程序中鼠標事件處理技術。

2、實驗內容和步驟

實驗1： 導入第11章示例程序，測試程序並進行代碼註釋。

測試程序1：

l 在elipse IDE中調試運行教材443頁-444頁程序11-1，結合程序運行結果理解程序；

原代碼以下：

package button;

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

/**
 * A frame with a button panel
 */
public class ButtonFrame extends JFrame
{
    //屬性的定義
   private JPanel buttonPanel;//內容窗格對象
   private static final int DEFAULT_WIDTH = 300;//窗口寬度
   private static final int DEFAULT_HEIGHT = 200;//窗口高度

   public ButtonFrame()
   {      
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);//更改了GUI界面的寬度和高度

      // 生成三個按鈕對象
      JButton yellowButton = new JButton("yellow");
      JButton blueButton = new JButton("Blue");
      JButton redButton = new JButton("Red");

      buttonPanel = new JPanel();

      // 向buttonPanel內容窗格添加三個按鈕組件
      buttonPanel.add(yellowButton);
      buttonPanel.add(blueButton);
      buttonPanel.add(redButton);

      // 添加內容窗格
      add(buttonPanel);

      // 註冊監聽器類對象
      ColorAction yellowAction = new ColorAction(Color.YELLOW);
      ColorAction blueAction = new ColorAction(Color.BLUE);
      ColorAction redAction = new ColorAction(Color.RED);

      // 監聽器類對象和組件對應
      yellowButton.addActionListener(yellowAction);
      blueButton.addActionListener(blueAction);
      redButton.addActionListener(redAction);
   }

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

      public ColorAction(Color c)
      {
         backgroundColor = c;
      }
     
      public void actionPerformed(ActionEvent event)
      {
         buttonPanel.setBackground(backgroundColor);
      }
   }
}

 

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();//生成GUI類對象frame
         frame.setTitle("ButtonTest");//設置程序的名字
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//窗口的退出按鈕起做用
         frame.setVisible(true);//可視化，使得程序可見
      });
   }
}

 

l 在事件處理相關代碼處添加註釋；

l 用lambda表達式簡化程序；

簡化程序ButtonFrame①

package shiyan;

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

/**
 * A frame with a button panel
 */
public class ButtonFrame extends JFrame {
    // 屬性的定義
    private JPanel buttonPanel;// 內容窗格對象
    private static final int DEFAULT_WIDTH = 300;// 窗口寬度
    private static final int DEFAULT_HEIGHT = 200;// 窗口高度

    public ButtonFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);// 更改了GUI界面的寬度和高度

        // 生成三個按鈕對象
        /*
         * JButton yellowButton = new JButton("yellow"); JButton blueButton = new
         * JButton("Blue"); JButton redButton = new JButton("Red");
         */
        buttonPanel = new JPanel();

        // 向buttonPanel內容窗格添加三個按鈕組件
        /*
         * buttonPanel.add(yellowButton); buttonPanel.add(blueButton);
         * buttonPanel.add(redButton);
         */
        // 添加內容窗格
        add(buttonPanel);

        // 註冊監聽器類對象
        /*
         * ColorAction yellowAction = new ColorAction(Color.YELLOW); ColorAction
         * blueAction = new ColorAction(Color.BLUE); ColorAction redAction = new
         * ColorAction(Color.RED);
         */

        // 監聽器類對象和組件對應
        /*
         * yellowButton.addActionListener(yellowAction);
         * blueButton.addActionListener(blueAction);
         * redButton.addActionListener(redAction);
         */
        makeButton("yellow", Color.YELLOW);
        makeButton("blue", Color.BLUE);
        makeButton("red", Color.RED);
        makeButton("green", Color.GREEN);

    }

    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// ColorAction爲監聽器類
    {
        private Color backgroundColor;

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

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

 

簡化程序ButtonFrame②

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);

        // create buttons
        /*
         * JButton yellowButton = new JButton("Yellow"); JButton blueButton = new
         * JButton("Blue"); JButton redButton = new JButton("Red");
         */
        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);
        makeButton("green", Color.GREEN);

    }

    public void makeButton(String name, Color backgroundColor) {
        JButton button = new JButton(name);
        buttonPanel.add(button);
        /*
         * ColorAction action = new ColorAction(backgroundColor);
         * button.addActionListener(action);
         */
        button.addActionListener(new ActionListener() {

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

/**
 * 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); } } }
 */

 

l 掌握JButton組件的基本API；

l 掌握Java中事件處理的基本編程模型。

測試程序2：

l 在elipse IDE中調試運行教材449頁程序11-2，結合程序運行結果理解程序；

l 在組件觀感設置代碼處添加註釋；

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.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)
   {
      // 窗格中添加按鈕

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

      // 設定按鈕動做
      button.addActionListener(event -> {
         // 按鈕動做: 切換到新的外觀和感受
         try
         {
            UIManager.setLookAndFeel(className);
            SwingUtilities.updateComponentTreeUI(this);
            pack();
         }
         catch (Exception e)
         {
            e.printStackTrace();
         }
      });
   }
}

 

l 瞭解GUI程序中觀感的設置方法。

測試程序3：

l 在elipse IDE中調試運行教材457頁-458頁程序11-3，結合程序運行結果理解程序；

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();

      // 定義動做
      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);

      // 爲這些動做添加按鈕
      buttonPanel.add(new JButton(yellowAction));
      buttonPanel.add(new JButton(blueAction));
      buttonPanel.add(new JButton(redAction));

//將Y、B和R鍵與名稱聯繫起來
      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");

      // 把名字和行動聯繫起來
      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);
      }
   }
}

 

 

l 掌握AbstractAction類及其動做對象；

l 掌握GUI程序中按鈕、鍵盤動做映射到動做對象的方法。

測試程序4：

l 在elipse IDE中調試運行教材462頁程序11-四、11-5，結合程序運行結果理解程序；

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; // 包含鼠標光標的正方形
   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;

      // 繪製全部方塊
      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)
      {
         // 若是光標不在正方形內，則添加一個新的正方形
         current = find(event.getPoint());
         if (current == null) add(event.getPoint());
      }

      public void mouseClicked(MouseEvent event)
      {
         // 若是雙擊，則刪除當前正方形
         current = find(event.getPoint());
         if (current != null && event.getClickCount() >= 2) remove(current);
      }
   }

   private class MouseMotionHandler implements MouseMotionListener
   {
      public void mouseMoved(MouseEvent event)
      {
         //若是鼠標光標位於內部，則將其設置爲交叉頭髮
//矩形
         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();

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

 

l 掌握GUI程序中鼠標事件處理技術。

實驗2：結對編程練習

利用班級名單文件、文本框和按鈕組件，設計一個有以下界面（圖1）的點名器，要求用戶點擊開始按鈕後在文本輸入框隨機顯示2017級網絡與信息安全班同窗姓名，如圖2所示，點擊中止按鈕後，文本輸入框再也不變換同窗姓名，此同窗則是被點到的同窗姓名。

 

圖1 點名器啓動界面

 

圖2 點名器點名界面

實驗結果以下：

 代碼以下：

package 點名器;

import java.awt.EventQueue;

import javax.swing.JFrame;

/**
 * @version 1.34 2015-05-12
 * @author Cay Horstmann
 */
public class Demo
{
   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 點名器;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
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
 */
public class ButtonFrame extends JFrame {
    private JPanel buttonPanel;
    private static final int DEFAULT_WIDTH = 300 * 2;
    private static final int DEFAULT_HEIGHT = 200 * 2;
    private ArrayList<String> arrayList;

    public ButtonFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
        buttonPanel = new JPanel();
        buttonPanel.setLayout(null);
        JLabel jLabel = new JLabel("點名器");
        JButton jButton = new JButton("開始");
        jLabel.setBounds(250, 80, 100, 60);
        jButton.setBounds(250, 150, 100, 60);
        arrayList = new ArrayList<>();
        File file = new File("E:/學生.txt");
        FileInputStream fis;
        try {
            fis = new FileInputStream(file);
            InputStreamReader in = new InputStreamReader(fis);
            BufferedReader buf = new BufferedReader(in);
            String readLine;
            while ((readLine = buf.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();
        }

        jButton.addActionListener(new ActionListener() {
            Timer timer;

            public void actionPerformed(ActionEvent e) {
                if (jButton.getText().equals("開始")) {

                    timer = new Timer();
                    TimerTask timerTask = new TimerTask() {
                        public void run() {
                            jButton.setText("中止");
                            jLabel.setText(arrayList.get((int) (Math.random() * 42)));

                        }
                    };
                    timer.schedule(timerTask, 0, 15);
                }
                if (jButton.getText().equals("中止")) {
                    timer.cancel();
                    jButton.setText("開始");
                }
            }
        });
        jButton.setBackground(Color.orange);
        buttonPanel.add(jLabel);
        buttonPanel.add(jButton);
        add(buttonPanel);
    }

}

實驗總結

 

掌握了事件處理的基本原理和用途；掌握了AWT事件模型的工做機制和事件處理的基本編程模型；瞭解了GUI界面組件觀感設置方法；