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。