控制台程序。
定义监听器类有许多方式。下面把监听器类定义为单独的类MouseHandler:
1 // Mouse event handler for a selection button 2 import java.awt.Cursor; 3 import java.awt.event.*; 4 5 public class MouseHandler extends MouseAdapter { 6 Cursor handCursor = new Cursor(Cursor.HAND_CURSOR); 7 Cursor defaultCursor = new Cursor(Cursor.DEFAULT_CURSOR); 8 9 // Handle mouse entering the selection button 10 @Override 11 public void mouseEntered(MouseEvent e) { 12 e.getComponent().setCursor(handCursor); // Switch to hand cursor 13 } 14 // Handle mouse exiting the selection button 15 @Override 16 public void mouseExited(MouseEvent e) { 17 e.getComponent().setCursor(defaultCursor); // Change to default cursor 18 } 19 }
然后修改createGUI()方法中的循环，为applet添加鼠标监听器即可：
1 // Applet to generate lottery entries 2 import javax.swing.*; 3 import java.awt.*; 4 import java.awt.event.*; 5 import java.util.Random; // For random number generator 6 7 @SuppressWarnings("serial") 8 public class Lottery extends JApplet { 9 // Generate NUMBER_COUNT random selections from the VALUES array 10 private static int[] getNumbers() { 11 int[] numbers = new int[NUMBER_COUNT]; // Store for the numbers to be returned 12 int candidate = 0; // Stores a candidate selection 13 for(int i = 0; i < NUMBER_COUNT; ++i) { // Loop to find the selections 14 15 search: 16 // Loop to find a new selection different from any found so far 17 while(true) { 18 candidate = VALUES[choice.nextInt(VALUES.length)]; 19 for(int j = 0 ; j < i ; ++j) { // Check against existing selections 20 if(candidate==numbers[j]) { // If it is the same 21 continue search; // get another random selection 22 } 23 } 24 numbers[i] = candidate; // Store the selection in numbers array 25 break; // and go to find the next 26 } 27 } 28 return numbers; // Return the selections 29 } 30 31 // Initialize the applet 32 @Override 33 public void init() { 34 SwingUtilities.invokeLater( // Create interface components 35 new Runnable() { // on the event dispatching thread 36 public void run() { 37 createGUI(); 38 } 39 }); 40 } 41 42 // Create User Interface for applet 43 public void createGUI() { 44 // Set up the selection buttons 45 Container content = getContentPane(); 46 content.setLayout(new GridLayout(0,1)); // Set the layout for the applet 47 48 // Set up the panel to hold the lucky number buttons 49 JPanel buttonPane = new JPanel(); // Add the pane containing numbers 50 51 // Let's have a fancy panel border 52 buttonPane.setBorder(BorderFactory.createTitledBorder( 53 BorderFactory.createEtchedBorder(Color.cyan, 54 Color.blue), 55 "Every One a Winner!")); 56 57 int[] choices = getNumbers(); // Get initial set of numbers 58 MouseHandler mouseHandler = new MouseHandler(); // Create the listener 59 for(int i = 0 ; i < NUMBER_COUNT ; ++i) { 60 luckyNumbers[i] = new Selection(choices[i]); 61 luckyNumbers[i].addActionListener(luckyNumbers[i]); // Button is it's own listener 62 luckyNumbers[i].addMouseListener(mouseHandler); 63 buttonPane.add(luckyNumbers[i]); 64 } 65 content.add(buttonPane); 66 67 // Add the pane containing control buttons 68 JPanel controlPane = new JPanel(new FlowLayout(FlowLayout.CENTER, 5, 10)); 69 70 // Add the two control buttons 71 JButton button; // A button variable 72 Dimension buttonSize = new Dimension(100,20); // Button size 73 74 controlPane.add(button = new JButton("Lucky Numbers!")); 75 button.setBorder(BorderFactory.createRaisedBevelBorder()); 76 button.addActionListener(new HandleControlButton(PICK_LUCKY_NUMBERS)); 77 button.setPreferredSize(buttonSize); 78 79 controlPane.add(button = new JButton("Color")); 80 button.setBorder(BorderFactory.createRaisedBevelBorder()); 81 button.addActionListener(new HandleControlButton(COLOR)); 82 button.setPreferredSize(buttonSize); 83 84 content.add(controlPane); 85 } 86 87 // Class defining custom buttons showing lottery selection 88 private class Selection extends JButton implements ActionListener { 89 // Constructor 90 public Selection(int value) { 91 super(Integer.toString(value)); // Call base constructor and set the label 92 this.value = value; // Save the value 93 setBackground(startColor); 94 setBorder(BorderFactory.createRaisedBevelBorder()); // Add button border 95 setPreferredSize(new Dimension(80,20)); 96 } 97 98 // Handle selection button event 99 public void actionPerformed(ActionEvent e) { 100 // Change this selection to a new selection 101 int candidate = 0; 102 while(true) { // Loop to find a different selection 103 candidate = VALUES[choice.nextInt(VALUES.length)]; 104 if(!isCurrentSelection(candidate)) { // If it is different 105 break; // end the loop 106 } 107 } 108 setValue(candidate); // We have one so set the button value 109 } 110 // Set the value for the selection 111 public void setValue(int value) { 112 setText(Integer.toString(value)); // Set value as the button label 113 this.value = value; // Save the value 114 } 115 116 // Check the value for the selection 117 boolean hasValue(int possible) { 118 return value==possible; // Return true if equals current value 119 } 120 121 // Check the current choices 122 boolean isCurrentSelection(int possible) { 123 for(int i = 0 ; i < NUMBER_COUNT ; ++i) { // For each button 124 if(luckyNumbers[i].hasValue(possible)) { // check against possible 125 return true; // Return true for any = 126 } 127 } 128 return false; // Otherwise return false 129 } 130 131 private int value; // Value for the selection button 132 } 133 134 // Class defining a handler for a control button 135 private class HandleControlButton implements ActionListener { 136 // Constructor 137 public HandleControlButton(int buttonID) { 138 this.buttonID = buttonID; // Store the button ID 139 } 140 141 // Handle button click 142 public void actionPerformed(ActionEvent e) { 143 switch(buttonID) { 144 case PICK_LUCKY_NUMBERS: 145 int[] numbers = getNumbers(); // Get maxCount random numbers 146 for(int i = 0 ; i < NUMBER_COUNT ; ++i) { 147 luckyNumbers[i].setValue(numbers[i]); // Set the button VALUES 148 } 149 break; 150 case COLOR: 151 Color color = new Color( 152 flipColor.getRGB()^luckyNumbers[0].getBackground().getRGB()); 153 for(int i = 0 ; i < NUMBER_COUNT ; ++i) 154 luckyNumbers[i].setBackground(color); // Set the button colors 155 break; 156 } 157 } 158 159 private int buttonID; 160 } 161 162 final static int NUMBER_COUNT = 6; // Number of lucky numbers 163 final static int MIN_VALUE = 1; // Minimum in range 164 final static int MAX_VALUE = 49; // Maximum in range 165 final static int[] VALUES = new int[MAX_VALUE-MIN_VALUE+1]; // Array of possible VALUES 166 static { // Initialize array 167 for(int i = 0 ; i < VALUES.length ; ++i) 168 VALUES[i] = i + MIN_VALUE; 169 } 170 171 // An array of custom buttons for the selected numbers 172 private Selection[] luckyNumbers = new Selection[NUMBER_COUNT]; 173 final public static int PICK_LUCKY_NUMBERS = 1; // Select button ID 174 final public static int COLOR = 2; // Color button ID 175 176 // swap colors 177 Color flipColor = new Color(Color.YELLOW.getRGB()^Color.RED.getRGB()); 178 179 Color startColor = Color.YELLOW; // start color 180 181 private static Random choice = new Random(); // Random number generator 182 }
Html文件和上一个例子一样。
对于鼠标是动作源的任何组件来说，都可以应用上述技巧。