201771010101 白瑪次仁 《2018面向物件程式設計(Java)》第十三週學習總結
實驗十三 圖形介面事件處理技術
實驗時間 2018-11-22
學習總結:
Compoment類提供的功能:
–基本的繪畫支援。
–外形控制。
–大小和位置控制。
–影象處理。
–元件狀態控制
每個容器:
– add() 方法向容器新增某個元件,
– remove()方法從容器中刪除某個元件。
容器通過方法 setLayout () 設定某種佈局。
Swing比AWT 元件具有更強的實用性和美觀性。
Swing元件必須新增到一個與 Swing 頂層容器相 關聯的內容面板( contentpane)上。
事件物件 (event object):Java 將事件的相關資訊 將事件的相關資訊 封裝在一個事件物件中 ,所有的事件物件都最終派生於 java.util.EventObject 類。不 同的事件源可以產生不 同的類別的事件。
事件源來通知事件發生,然後監聽器物件註冊事件源。
註冊監聽器方法eventSourceObject.addEvenListtener(evenListenerObject)
能夠觸發動作 事件的,主要包括:
(1)點選按鈕
(2)雙擊一個列表中的選項;
(3)選擇選單項;
(4)在文字框中輸入回車 。
監聽器類必須實現與事件源相對應的介面 ,即必 須提供介面中方法 的實現 。
當程式使用者試圖關閉一個框架視窗時, Jframe 物件就是 WindowEvent 的事件源。
視窗監聽器必須是實現 WindowListener類的一個物件 ,WindowListener介面中有七個方法.
Swing 包提供了非常實用的機制來封裝命令 ,並將它 們連線到多個事件源 ,這就是 Action 介面 。
圖形編輯器應用程式 ,其允許使用者在畫布上放置、移動和擦除方塊
1. 當滑鼠點選在所有小方塊的畫素之外時,會繪製一個新的小方塊;
2. 當雙擊一個小方塊內部時,會擦除該;
3. 當滑鼠在窗體上移動時,如果經過一個小方塊的內部,游標會變成一個十字形;
4. 實現用滑鼠拖動小方塊。
監聽滑鼠移動事件,實現 MouseMotionListener 介面。
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事件模型的工作機制;
(3) 掌握事件處理的基本程式設計模型;
(4) 瞭解GUI介面元件觀感設定方法;
(5) 掌握WindowAdapter類、AbstractAction類的用法;
(6) 掌握GUI程式中滑鼠事件處理技術。
2、實驗內容和步驟
實驗1: 匯入第11章示例程式,測試程式並進行程式碼註釋。
測試程式1:
l 在elipse IDE中除錯執行教材443頁-444頁程式11-1,結合程式執行結果理解程式;
l 在事件處理相關程式碼處添加註釋;
l 用lambda表示式簡化程式;
l 掌握JButton元件的基本API;
l 掌握Java中事件處理的基本程式設計模型。
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()//構造器 { setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);//決定框架的大小 // create buttons 構造器按鈕 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);//將按鈕新增到面板中 buttonPanel.add(blueButton); buttonPanel.add(redButton); // add panel to frame add(buttonPanel); // create button actions //每種顏色構造一個物件,並將這些物件設定為按鈕監聽器 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. */ //實現一個監聽器的介面 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");//應用名 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); }
測試程式2:
l 在elipse IDE中除錯執行教材449頁程式11-2,結合程式執行結果理解程式;
l 在元件觀感設定程式碼處添加註釋;
l 瞭解GUI程式中觀感的設定方法。
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();//例項化一個新的JPanel //獲取所有的顯示樣式 UIManager.LookAndFeelInfo[] infos = UIManager.getInstalledLookAndFeels(); for (UIManager.LookAndFeelInfo info : infos) makeButton(info.getName(), info.getClassName()); add(buttonPanel);//增加了按鍵點選事件 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
//向面板新增按鈕 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物件 frame.setTitle("PlafTest");
//設定組建的自定義標題測試按鈕 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); } }
測試程式3:
l 在elipse IDE中除錯執行教材457頁-458頁程式11-3,結合程式執行結果理解程式;
l 掌握AbstractAction類及其動作物件;
l 掌握GUI程式中按鈕、鍵盤動作對映到動作物件的方法。
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); }); } }
} }
測試程式4:
l 在elipse IDE中除錯執行教材462頁程式11-4、11-5,結合程式執行結果理解程式;
l 掌握GUI程式中滑鼠事件處理技術。
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;//定義創造的正方形的邊長 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());
//新增一個我們實現的類,這個類繼承了監測滑鼠點選情況的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)
//轉換我們需要使用的型別
//繪製所有正方形 { 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();
//獲取x和y的座標 current = new Rectangle2D.Double(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH); squares.add(current); repaint();//重繪影象 } /** * Removes a square from the collection. * @param s the square to remove */ public void remove(Rectangle2D s) { if (s == null) return;
//如果要移除的內容為空,直接返回 if (s == current) current = null; squares.remove(s); repaint();//重繪component的方法 } private class MouseHandler extends MouseAdapter { public void mousePressed(MouseEvent event)//滑鼠按下方法 { // 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());//向框架中新增一個JComponent的例項 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");
//設定組建的定義標題測試按鈕 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); }); } }
實驗2:結對程式設計練習
利用班級名單檔案、文字框和按鈕元件,設計一個有如下介面(圖1)的點名器,要求使用者點選開始按鈕後在文字輸入框隨機顯示2017級網路與資訊安全班同學姓名,如圖2所示,點選停止按鈕後,文字輸入框不再變換同學姓名,此同學則是被點到的同學姓名。
圖1 點名器啟動介面
圖2 點名器點名介面
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("開始"); but.setBounds(100,150,100,40); show = new JButton("隨機點名"); 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("點名"); 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()=="開始"){ 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("開始"); but.setBackground(Color.WHITE); show.setBackground(Color.magenta); } } }
實驗總結:這次實驗的學習中知道了圖形編輯器應用程式 ,其允許使用者在畫布上放置、移動和擦除方塊等等,
更好想學敲程式碼。