[Design-Pattern]工厂模式

Java版本

 1 package interfaces;
 2
 3 interface Service {
 4     void method1();
 5     void method2();
 6 }
 7
 8 interface ServiceFactory {
 9     Service getService();
10 }
11
12 class Implementation1 implements Service {
13     Implementation1() {}
14     public void method1() { System.out.println("Implementation1 method1"); }
15     public void method2() { System.out.println("Implementation1 method2"); }
16 }
17
18 class Implementation1Factory implements ServiceFactory {
19     public Service getService() {
20         return new Implementation1();
21     }
22 }
23
24 class Implementation2 implements Service {
25     Implementation2() {}
26     public void method1() { System.out.println("Implementation2 method1"); }
27     public void method2() { System.out.println("Implementation2 method2"); }
28 }
29
30 class Implementation2Factory implements ServiceFactory {
31     public Service getService() {
32         return new Implementation2();
33     }
34 }
35
36 public class Factories {
37     public static void serviceConsumer(ServiceFactory fact) {
38         Service s = fact.getService();
39         s.method1();
40         s.method2();
41     }
42     public static void main(String[] args) {
43         serviceConsumer(new Implementation1Factory());
44         serviceConsumer(new Implementation2Factory());
45     }
46 }

C++版本

 1 #include <stdio.h>
 2
 3 class Service {
 4 public:
 5     virtual void method1() = 0;
 6     virtual void method2() = 0;
 7 };
 8
 9 class ServiceFactory {
10 public:
11     virtual Service* getService() = 0;
12 };
13
14 class Implementation1 :public Service {
15 public:
16     Implementation1() {}
17     virtual void method1() { printf("Implementation1 method1\n"); }
18     virtual void method2() { printf("Implementation1 method2\n"); }
19 };
20
21 class Implementation2 :public Service {
22 public:
23     Implementation2() {}
24     virtual void method1() { printf("Implementation2 method1\n"); }
25     virtual void method2() { printf("Implementation2 method2\n"); }
26 };
27
28 class Implementation1ServiceFactory :public ServiceFactory {
29 public:
30     Implementation1ServiceFactory() {}
31     virtual Service* getService() {
32         return new Implementation1();
33     }
34 };
35
36 class Implementation2ServiceFactory :public ServiceFactory {
37 public:
38     Implementation2ServiceFactory() {}
39     virtual Service* getService() {
40         return new Implementation2();
41     }
42 };
43
44 void serviceConsumer(ServiceFactory* fact) {
45     Service* s = fact->getService();
46     s->method1();
47     s->method2();
48 }
49
50 int main()
51 {
52     serviceConsumer(new Implementation1ServiceFactory());
53     serviceConsumer(new Implementation2ServiceFactory());
54     return 0;
55 }

Java使用匿名内部类后的版本

 1 package innerclasses;
 2
 3 interface Service {
 4     void method1();
 5     void method2();
 6 }
 7
 8 interface ServiceFactory {
 9     Service getService();
10 }
11
12 class Implementation1 implements Service {
13     private Implementation1() {}
14     public void method1() { System.out.println("Implementation1 method1"); }
15     public void method2() { System.out.println("Implementation1 method2"); }
16     public static ServiceFactory factory = new ServiceFactory() {
17         @Override
18         public Service getService() {
19             return new Implementation1();
20         }
21     };
22 }
23
24 class Implementation2 implements Service {
25     private Implementation2() {}
26     public void method1() { System.out.println("Implementation2 method1"); }
27     public void method2() { System.out.println("Implementation2 method2"); }
28     public static ServiceFactory factory = new ServiceFactory() {
29         @Override
30         public Service getService() {
31             return new Implementation2();
32         }
33     };
34 }
35
36 public class Factories {
37     public static void serviceConsumer(ServiceFactory fact) {
38         Service s = fact.getService();
39         s.method1();
40         s.method2();
41     }
42     public static void main(String[] args) {
43         serviceConsumer(Implementation1.factory);
44         serviceConsumer(Implementation2.factory);
45     }
46 }

可以看出，Java在使用了匿名内部类后，代码明显少了很多，省去了Implementation1ServiceFactory、Implementation2ServiceFactory类的创建。