Java-动态代理-初步

一、概述

1.目标：要在Tank的move()方法做时间代理及日志代理(可以设想以后还要增加很多代理处理)，且代理间的顺序可活更换

2.思路：

(1)聚合：由于代理类及被代理类都实现了movable接口，代理类聚合了被代理类，所以可以灵活多变，具体看代码

(2)继承：继承不够灵活，具体看代码

二、代码

1.Movable.java

2.Tank.java

3.TankTimeProxy.java

4.TankLogProxy.java

5.Tank2Time.java

6.Tank3Log.java

7.Client.java

1.Movable.java

1 public interface Movable {
2     public void move();
3 }

2.Tank.java

 1 import java.util.Random;
 2
 3 public class Tank implements Movable {
 4
 5     @Override
 6     public void move() {
 7         System.out.println("Tank moving.......");
 8         try {
 9             Thread.sleep(new Random().nextInt(5000));
10         } catch (InterruptedException e) {
11             e.printStackTrace();
12         }
13     }
14
15 }

3.TankTimeProxy.java

 1 public class TankTimeProxy implements Movable {
 2
 3     Movable m;
 4
 5     public TankTimeProxy(Movable m) {
 6         this.m = m;
 7     }
 8
 9     @Override
10     public void move() {
11         System.out.println("Time Proxy start...........");
12         long start = System.currentTimeMillis();
13         m.move();
14         long end = System.currentTimeMillis();
15         System.out.println("花费时间："+(end - start));
16         System.out.println("Time Proxy end...........");
17     }
18
19 }

4.TankLogProxy.java

 1 public class TankLogProxy implements Movable {
 2
 3     Movable m;
 4
 5     public TankLogProxy(Movable m) {
 6         this.m = m;
 7     }
 8
 9     @Override
10     public void move() {
11         System.out.println("Log Proxy start...........");
12         m.move();
13         System.out.println("Log Proxy end...........");
14     }
15
16 }

5.Tank2Time.java

 1 public class Tank2Time extends Tank {
 2
 3     public void move(){
 4         System.out.println("Tank2 time  start...........");
 5         long start = System.currentTimeMillis();
 6         super.move();
 7         long end = System.currentTimeMillis();
 8         System.out.println("花费时间："+(end - start));
 9         System.out.println("Tank2 time end...........");
10     }
11 }

6.Tank3Log.java

1 public class Tank3Log extends Tank2Time {
2
3     public void move(){
4         System.out.println("Tank3Log  start...........");
5         super.move();
6         System.out.println("Tank3Log  end...........");
7     }
8 }

7.Client.java

 1 public class Client {
 2
 3     @Test
 4     public void testProxy(){
 5
 6         Tank t = new Tank();
 7         Movable m;
 8
 9         //一、聚合的方式(较灵活，因为实现了接口)
10         //1.1聚合方式的代理,先日志代理，后时间代理
11         TankTimeProxy ttp1 = new TankTimeProxy(t);
12         TankLogProxy tlp1 = new TankLogProxy(ttp1);
13
14         m = tlp1;
15         m.move();
16
17         System.out.println("\n==============================分隔线==========================\n");
18
19         //1.2聚合方式的代理,先时间代理，后日志代理(可以灵活切换顺序)
20         TankLogProxy tlp2 = new TankLogProxy(t);
21         TankTimeProxy ttp2 = new TankTimeProxy(tlp2);
22
23         m = ttp2;
24         m.move();
25
26         System.out.println("\n==============================分隔线==========================\n");
27
28         //二、继承的方式
29         //2.1代理时间
30         Tank2Time t2 = new Tank2Time();
31         t2.move();
32
33         System.out.println("\n==============================分隔线==========================\n");
34
35         //2.2先代理日志，后时间，不能灵活切换
36         Tank3Log t3 = new Tank3Log();
37         t3.move();
38
39
40
41     }
42 }

三、运行结果

四、小结

凡是要求灵活多变的功能，多数用接口多态实现