这个例子体现了aop但是怎么体会不到指点下？

java 代码

//: generics/Mixins.java
import java.util.*;

interface TimeStamped { long getStamp(); }

class TimeStampedImp implements TimeStamped {
 private final long timeStamp;
 public TimeStampedImp() {
 timeStamp = new Date().getTime();
 }
 public long getStamp() { return timeStamp; }
}

interface SerialNumbered { long getSerialNumber(); }

class SerialNumberedImp implements SerialNumbered {
 private static long counter = 1;
 private final long serialNumber = counter++;
 public long getSerialNumber() { return serialNumber; }
}

interface Basic {
 public void set(String val);
 public String get();
}

class BasicImp implements Basic {
 private String value;
 public void set(String val) { value = val; }
 public String get() { return value; }
}

class Mixin extends BasicImp
implements TimeStamped, SerialNumbered {
 private TimeStamped timeStamp = new TimeStampedImp();
 private SerialNumbered serialNumber =
 new SerialNumberedImp();
 public long getStamp() { return timeStamp.getStamp(); }
 public long getSerialNumber() {
 return serialNumber.getSerialNumber();
 }
}

public class Mixins {
 public static void main(String[] args) {
 Mixin mixin1 = new Mixin(), mixin2 = new Mixin();
 mixin1.set("test string 1");
 mixin2.set("test string 2");
 System.out.println(mixin1.get() + " " +
 mixin1.getStamp() + " " + mixin1.getSerialNumber());
 System.out.println(mixin2.get() + " " +
 mixin2.getStamp() + " " + mixin2.getSerialNumber());
 }
} /* Output: (Sample)
test string 1 1132437151359 1
test string 2 1132437151359 2
*///:~