狄慧201771010104《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

一、知识点总结

 1、AWT事件处理机制的概要：

1>监听器对象是一个实现了特定监听器接口的类的实例；

2>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；

3>当事件发生时，事件源将事件对象传递给所有注册的监听器；

4>监听器对象将利用事件对象中的信息决定如何对事件做出响应。

2、改变观感：

在默认情况下，Swing程序使用Metal观感，可以采用两种方式改变观感：

1>在Java安装的子目录jre/lib下有一个文件swing.properties。在这个文件中，将属性swing.defaultlaf设置为所希望的观感类名；

2>动态的改变观感。需要调用静态的UIManager.setLookAndFeel方法，并提供所想要的观感类名，然后再调用静态方法SwingUtilities.updataComponentTreeUI来刷新全部的组件集。

3、用同一个动作响应按钮、菜单项或按键的方式：

1>实现一个扩展于AbstractAction类的类。多个相关的动作可以使用同一个类；

2>构造一个动作类的对象；

3>使用动作对象创建按钮或菜单项，构造器将从动作对象中读取标签文本和图标；

4>为了能够通过按键触发动作，必须额外地执行几步操作。首先定位定位顶层窗口组件；

5>然后，得到顶层组件的WHEN_ANCESTOR_OF_FOCUS_COMPONENT输入映射。为需要的按键创建一个KeyStrike对象。创建一个描述动作字符串这样的动作键对象。将（按键、动作键）对添加到输入映射中；

6>最后，得到顶层组件的动作映射。将（动作键、动作对象）添加到映射中。

4、AWT事件分为底层事件和语义事件。

1>语义事件：表示用户动作的事件。点击事件；

2>底层事件：形成那些事件的事件。在点击按钮时，包含了按下鼠标、连续移动鼠标、抬起鼠标事件。

二、实验内容

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。

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();//生成ButtonFrame类对象frame
         frame.setTitle("ButtonTest");//设置窗体标题
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置关闭按钮
         frame.setVisible(true);//窗口是否可见
      });
   }
}

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;//JPanel 是一般轻量级容器
   private static final int DEFAULT_WIDTH = 600;//静态常量
   private static final int DEFAULT_HEIGHT = 400;

   public ButtonFrame()
   {      
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);//设置组件大小

      // create buttons
      //生成三个按钮对象
      JButton yellowButton = new JButton("Yellow");//黄色按钮
      JButton blueButton = new JButton("Blue");//蓝色按钮
      JButton redButton = new JButton("Red");//红色按钮

      buttonPanel = new JPanel();

      // add buttons to panel
      //添加三个按钮组件
      buttonPanel.add(yellowButton);
      buttonPanel.add(blueButton);
      buttonPanel.add(redButton);

      // add panel to frame
      add(buttonPanel);

      // create button actions
      //生成三个监听器类对象
      ColorAction yellowAction = new ColorAction(Color.YELLOW);
      ColorAction blueAction = new ColorAction(Color.BLUE);
      ColorAction redAction = new ColorAction(Color.RED);

      // associate actions with buttons
      //把监听器类对象和组件关联
      yellowButton.addActionListener(yellowAction);
      blueButton.addActionListener(blueAction);
      redButton.addActionListener(redAction);
   }

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

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

      public void actionPerformed(ActionEvent event)//更改容器的背景色
      {
         buttonPanel.setBackground(backgroundColor);
      }
   }
}

ButtonFrame

简化后

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();//生成ButtonFrame类对象frame
         frame.setTitle("ButtonTest");//设置窗体标题
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置关闭按钮
         frame.setVisible(true);//窗口是否可见
      });
   }

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;// JPanel 是一般轻量级容器
    private static final int DEFAULT_WIDTH = 600;// 静态常量
    private static final int DEFAULT_HEIGHT = 400;

    public ButtonFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);// 设置组件大小
        buttonPanel = new JPanel();
        add(buttonPanel);
        makeButton("yellow", Color.YELLOW);
        makeButton("blue", Color.BLUE);
        makeButton("red", Color.RED);
        makeButton("green", Color.GREEN);
    }

    /**
     * An action listener that sets the panel's background color.
     */
    // 监听器类
    /*
     * private class ColorAction implements ActionListener { private Color
     * backgroundColor;
     * 
     * public ColorAction(Color c) { backgroundColor = c; }
     * 
     * public void actionPerformed(ActionEvent event)// 更改容器的背景色 {
     * buttonPanel.setBackground(backgroundColor); } }
     */
    public void makeButton(String name, Color backgroundColor) {
        JButton button = new JButton(name);
        buttonPanel.add(button);
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent enent) {
                buttonPanel.setBackground(backgroundColor);
            }
        });
    }
}

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();//生成ButtonFrame类对象frame
         frame.setTitle("ButtonTest");//设置窗体标题
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置关闭按钮
         frame.setVisible(true);//窗口是否可见
      });
   }
}

ButtonTest

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;// JPanel 是一般轻量级容器
    private static final int DEFAULT_WIDTH = 600;// 静态常量
    private static final int DEFAULT_HEIGHT = 400;

    public ButtonFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);// 设置组件大小
        buttonPanel = new JPanel();
        add(buttonPanel);
        makeButton("yellow", Color.YELLOW);
        makeButton("blue", Color.BLUE);
        makeButton("red", Color.RED);
        makeButton("green", Color.GREEN);
    }

    /**
     * An action listener that sets the panel's background color.
     */
    public void makeButton(String name, Color backgroundColor) {
        JButton button = new JButton(name);
        buttonPanel.add(button);
        button.addActionListener((e)-> {
                buttonPanel.setBackground(backgroundColor);
        });
    }
}

ButtonFrame

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");//设置窗体标题
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

PlafTest

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);//添加组件
      pack();//调整窗口大小
   }

   /**
    * 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)
   {
      // add button to panel

      JButton button = new JButton(name);//创建新按钮
      buttonPanel.add(button);

      // set button action

      button.addActionListener(event -> {
         // button action: switch to the new look-and-feel
         try
         {
            UIManager.setLookAndFeel(className);
            SwingUtilities.updateComponentTreeUI(this);//简单的外观更改
            pack();
         }
         catch (Exception e)
         {
            e.printStackTrace();//打印堆栈信息
         }
      });
   }
}

PlafFrame

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);
      });
   }
}

ActionTest

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);//设置组件大小

      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
      //添加三个组件
      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);//InputMap 提供输入事件
      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();//返回用于确定为特定 KeyStroke 绑定触发何种 Action 的 ActionMap
      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);//设置与指定键关联的 Value
         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);//设置组件的背景色
      }
   }
}

ActionFrame

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。

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

import mouse.MouseFrame;

/**
 * @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());//添加组件
      pack();//调整窗口大小
   }
}

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;//Rectangle2D 类描述通过位置 (x,y) 和尺寸 (w x h) 定义的矩形。 
   private Rectangle2D current; // the square containing the mouse cursor

   public MouseComponent()
   {
      squares = new ArrayList<>();//构造空列表
      current = null;

      addMouseListener(new MouseHandler());//添加指定的鼠标监听器
      addMouseMotionListener(new MouseMotionHandler());//添加指定的鼠标移动监听器
   }

   public Dimension getPreferredSize() { return new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT); }   
   //Dimension 类封装单个对象中组件的宽度和高度
   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();//返回Point2D 的 X 坐标
      double y = p.getY();

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

   /**
    * 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));//setCursor为指定的光标设置光标图像
      }

      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。

package 点名器啦;

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


public class 点名器1 extends JFrame implements ActionListener{
    private JButton but ;

    private JButton show;
    private static boolean flag = true;
    public static void main(String arguments []) {
         new 点名器1();

        }

public  点名器1(){

but = new JButton("开始");
but.setBounds(100,150,100,40);

show = new JButton("随机点名");
show.setBounds(100,100,180,30);
show.setFont(new Font("宋体",Font.BOLD,25));

add(but);

add(show);

setLayout(null);//布局管理器必须先初始化为空才能赋值
setVisible(true);
setResizable(false);
setBounds(200,200,400,400);
//setBackground(Color.red);不起作用
this.getContentPane().setBackground(Color.pink);
setTitle("点名");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

but.addActionListener(this);
}

    public void actionPerformed(ActionEvent e){
        int i=0;
        String names[]=new String[50];
        try {
            Scanner in=new Scanner(new File("E:\java\第十三周\studentnamelist.txt"));
            while(in.hasNextLine())
            {
                names[i]=in.nextLine();
                i++;
            }
        } catch (FileNotFoundException e1) {
            
            e1.printStackTrace();
        }

    
        if(but.getText()=="开始"){      

    show.setBackground(Color.blue);
    flag=true;
    new Thread(){   
        public void run(){
            while(点名器1.flag){
            Random r = new Random(); 
            int i= r.nextInt(47);
            show.setText(names[i]);
            }
        }
    }.start();
    but.setText("停止");//更改文本内容
    but.setBackground(Color.YELLOW);
}    
else if(but.getText()=="停止"){
    flag = false;
    but.setText("开始");
    but.setBackground(Color.WHITE);
    show.setBackground(Color.red);
}
    }



}

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三、实验总结

        本章我们学习了图形界面事件处理技术的知识，首先掌握了事件处理的基本原理，并学会了事件处理的基本编程模型；在老师的演示代码过程中，我清楚的学习到了lambda表达式的简便性，简化代码的好处和代码的多变性；在实验中，通过助教学长的演示和在书上源代码基础上进行的改编、添加，做出了点名器的代码程序，感觉又是一次充实的实验。