实验十三 图形界面事件处理技术
实验时间 2018-11-22
学习总结:
Compoment类提供的功能:
–基本的绘画支持。
–外形控制。
–大小和位置控制。
–图像处理。
–组件状态控制
每个容器:
– add() 方法向容器添加某个组件,
– remove()方法从容器中删除某个组件。
容器通过方法 setLayout () 设置某种布局。
Swing比AWT 组件具有更强的实用性和美观性。
Swing组件必须添加到一个与 Swing 顶层容器相 关联的内容面板( contentpane)上。
事件对象 (event object):Java 将事件的相关信息 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 同的类别的事件。
事件源来通知事件发生,然后监听器对象注册事件源。
注册监听器方法eventSourceObject.addEvenListtener(evenListenerObject)
能够触发动作 事件的,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;
(4)在文本框中输入回车 。
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 。
当程序用户试图关闭一个框架窗口时, Jframe 对象就是 WindowEvent 的事件源。
窗口监听器必须是实现 WindowListener类的一个对象 ,WindowListener接口中有七个方法.
Swing 包提供了非常实用的机制来封装命令 ,并将它 们连接到多个事件源 ,这就是 Action 接口 。
图形编辑器应用程序 ,其允许用户在画布上放置、移动和擦除方块
1. 当鼠标点击在所有小方块的像素之外时,会绘制一个新的小方块;
2. 当双击一个小方块内部时,会擦除该;
3. 当鼠标在窗体上移动时,如果经过一个小方块的内部,光标会变成一个十字形;
4. 实现用鼠标拖动小方块。
监听鼠标移动事件,实现 MouseMotionListener 接口。
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 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 = 400; private static final int DEFAULT_HEIGHT = 300; public ButtonFrame()//构造器 { setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);//决定框架的大小 // create buttons 构造器按钮 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);//将按钮添加到面板中 buttonPanel.add(blueButton); buttonPanel.add(redButton); // add panel to frame add(buttonPanel); // create button actions //每种颜色构造一个对象,并将这些对象设置为按钮监听器 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); } /** * An action listener that sets the panel‘s background color. */ //实现一个监听器的接口 private class ColorAction implements ActionListener { private Color backgroundColor; public ColorAction(Color c) { backgroundColor = c; } public void actionPerformed(ActionEvent event) { 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(() -> {//生成件面 JFrame frame = new ButtonFrame(); frame.setTitle("ButtonTest");//应用名 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); }
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 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();//实例化一个新的JPanel //获取所有的显示样式 UIManager.LookAndFeelInfo[] infos = UIManager.getInstalledLookAndFeels(); for (UIManager.LookAndFeelInfo info : infos) makeButton(info.getName(), info.getClassName()); add(buttonPanel);//增加了按键点击事件 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) { // add button to panel //向面板添加按钮 JButton button = new JButton(name); 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); pack(); } catch (Exception e) { e.printStackTrace(); } }); } }
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();//生成PlafFrame对象 frame.setTitle("PlafTest");//设置组建的自定义标题测试按钮 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); } }
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 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); }
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); }); } }
} }
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 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;//定义创造的正方形的边长 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());//添加一个我们实现的类,这个类继承了监测鼠标点击情况的MouseListener } 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)//转换我们需要使用的类型//绘制所有正方形 { 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();//获取x和y的坐标 current = new Rectangle2D.Double(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH); squares.add(current); repaint();//重绘图像 } /** * Removes a square from the collection. * @param s the square to remove */ public void remove(Rectangle2D s) { if (s == null) return;//如果要移除的内容为空,直接返回 if (s == current) current = null; squares.remove(s); repaint();//重绘component的方法 } private class MouseHandler extends MouseAdapter { public void mousePressed(MouseEvent event)//鼠标按下方法 { // 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(); } } } }
package mouse; import javax.swing.*; /** * A frame containing a panel for testing mouse operations */ public class MouseFrame extends JFrame { public MouseFrame() { add(new MouseComponent());//向框架中添加一个JComponent的实例 pack(); } }
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();//生成MonseFrame frame.setTitle("MouseTest");//设置组建的定义标题测试按钮 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); } }
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
图2 点名器点名界面
package dianming; 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 dianmingqi extends JFrame implements ActionListener{ private static final long serialVersionUID = 1L; private JButton but ; private JButton show; private static boolean flag = true; public static void main(String arguments []) { new dianmingqi(); } public dianmingqi(){ but = new JButton("开始"); but.setBounds(100,150,100,40); show = new JButton("随机点名"); show.setBounds(80,80,180,30); add(but); add(show); setLayout(null); setVisible(true); setResizable(false); setBounds(100,100,300,300); this.getContentPane().setBackground(Color.white); 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("D:\\studentnamelist.txt")); while(in.hasNextLine()) { names[i]=in.nextLine(); i++; } } catch (FileNotFoundException e1) { e1.printStackTrace(); } if(but.getText()=="开始"){ show.setBackground(Color.gray); flag=true; new Thread(){ public void run(){ while(dianmingqi.flag){ Random r = new Random(); int i= r.nextInt(47); show.setText(names[i]); } } }.start(); but.setText("停止"); but.setBackground(Color.darkGray); } else if(but.getText()=="停止"){ flag = false; but.setText("开始"); but.setBackground(Color.WHITE); show.setBackground(Color.magenta); } } }
实验总结:这次实验的学习中知道了图形编辑器应用程序 ,其允许用户在画布上放置、移动和擦除方块等等,
更好想学敲代码。
原文地址:https://www.cnblogs.com/baimaciren/p/10002052.html