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java

實驗時間 2018-11-22程序員

 

基礎知識:編程

 ⚫ 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。安全

⚫ 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。網絡

⚫ 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 同類別的事件併發

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。dom

⚫ 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。測試

⚫ 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。this

⚫ 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。spa

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。

 

點名器啓動界面

 

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;

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