1 import javax.swing.*;

 2 import java.awt.event.*;

 3 public class TestSourceListener {

 4

 5     public static void main(String[] args) {

 6         JFrame frame = new JFrame("TestSourceListener");

 7         JButton jbt = new JButton("OK");

 8

 9         //Create a source object源对象

10         frame.add(jbt);

11         frame.setSize(200, 200);

12         frame.setVisible(true);

13

14         //Create listener 监听器组件

15         MyListener listener = new MyListener();

16

17         //Register listeners 注册监听器组件

18         jbt.addActionListener(listener);

19     }

20 }

21 //监听器对象

22 class MyListener implements ActionListener{

23     //ActionEvent 事件类

24     public void actionPerformed(ActionEvent e){

25         System.out.println("I will process it!");

26     }

27 }

 1 /**

 2  * 创建自定义源组件

 3  * 源组件必须有适当的注册与注销方法，用来添加和删除监听器。

 4  * 源组件包含特定的代码，可以创建事件对象，以及通过传递这个事件对象去调用监听器的处理器。

 5  */

 6 import java.util.*;

 7 import java.awt.event.*;

 8 public class CourseWithActionEvent {

 9     private String courseName = "default name";

10     private ArrayList<String> students = new ArrayList<String>();

11     private int enrollmentCap = 10;

12

13     private ArrayList<ActionListener>actionlistenerList;

14

15     private CourseWithActionEvent() {

16     }

17     public CourseWithActionEvent(String courseName){

18         this.courseName = courseName;

19     }

20     public void addStudent(String student){

21         students.add(student);

22

23         if (students.size() > enrollmentCap) {

24             //创建事件对象

25             processEvent(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, null));

26         }

27     }

28

29     public String[] getStudents(){

30         return (String[])students.toArray();

31     }

32

33     public int getNumberOfStudents(){

34         return students.size();

35     }

36

37     public int getEnrollmentCap(){

38         return enrollmentCap;

39     }

40

41     public void setEnrollmentCap(int enrollmentCap){

42         this.enrollmentCap = enrollmentCap;

43     }

44

45     public synchronized void addActionListener(ActionListener listener){

46         if(actionlistenerList == null){

47             actionlistenerList = new ArrayList<ActionListener>(2);

48         }

49         if(!actionlistenerList.contains(listener)){

50             actionlistenerList.add(listener);

51         }

52     }

53

54     public synchronized void removeActionListener(ActionListener listener) {

55         if(actionlistenerList != null && actionlistenerList.contains(listener))

56             actionlistenerList.remove(listener);

57     }

58

59     private void processEvent(ActionEvent e) {

60         ArrayList list;

61

62         synchronized (this) {

63             if(actionlistenerList == null) return;

64             list = (ArrayList)actionlistenerList.clone();

65         }

66         //通过调用每个监听器的actionPerformed方法来通知actionlistenerList中的监听器进行处理。

67         for (int i = 0; i < list.size(); i++) {

68             ActionListener listener = (ActionListener)list.get(i);

69             listener.actionPerformed(e);

70         }

71     }

72 }