这个例子体现了aop但是怎么体会不到指点下？

java 代码

1. //: generics/Mixins.java
2. import java.util.*;
4. interface TimeStamped { long getStamp(); }

5. ---

6. class TimeStampedImp implements TimeStamped {
7. private final long timeStamp;
8. public TimeStampedImp() {
9. timeStamp = new Date().getTime();
10. }
11. public long getStamp() { return timeStamp; }
12. }

13. ---

14. interface SerialNumbered { long getSerialNumber(); }

15. ---

16. class SerialNumberedImp implements SerialNumbered {
17. private static long counter = 1;
18. private final long serialNumber = counter++;
19. public long getSerialNumber() { return serialNumber; }
20. }

21. ---

22. interface Basic {
23. public void set(String val);
24. public String get();
25. }

26. ---

27. class BasicImp implements Basic {
28. private String value;
29. public void set(String val) { value = val; }
30. public String get() { return value; }
31. }

32. ---

33. class Mixin extends BasicImp
34. implements TimeStamped, SerialNumbered {
35. private TimeStamped timeStamp = new TimeStampedImp();
36. private SerialNumbered serialNumber =
37. new SerialNumberedImp();
38. public long getStamp() { return timeStamp.getStamp(); }
39. public long getSerialNumber() {
40. return serialNumber.getSerialNumber();
41. }
42. }

43. ---

44. public class Mixins {
45. public static void main(String[] args) {
46. Mixin mixin1 = new Mixin(), mixin2 = new Mixin();
47. mixin1.set("test string 1");
48. mixin2.set("test string 2");
49. System.out.println(mixin1.get() + " " +
50. mixin1.getStamp() + " " + mixin1.getSerialNumber());
51. System.out.println(mixin2.get() + " " +
52. mixin2.getStamp() + " " + mixin2.getSerialNumber());
53. }
54. } /* Output: (Sample)
55. test string 1 1132437151359 1
56. test string 2 1132437151359 2
57. *///:~