java-对象的创建

  1 public static Boolean valueof(boolean a){
  2 		return a?Boolean.TRUE:Boolean.FALSE;
  3 	}

  1 public interface Service{
  2 		//service-specific methods go here
  3 	}
  4 	
  5 	public interface Provider{
  6 		Service newService();
  7 	}
  8 	
  9 	public  class Services{
 10 		private Services(){}
 11 		
 12 		private static final Map<String, Provider> providers=new ConcurrentHashMap<String, Provider>();
 13 		public static final String DEFAULT_PROVIDER_NAME="<def>";
 14 		
 15 		//provider registration API
 16 		public static void  registerDefaultProvider(Provider p){
 17 			registerProvider(DEFAULT_PROVIDER_NAME, p);
 18 		}
 19 		public static void registerProvider(String name,Provider p){
 20 			providers.put(name, p);
 21 		}
 22 		
 23 		//service access API
 24 		public static Service newInstance(){
 25 			return newInsance(DEFAULT_PROVIDER_NAME);
 26 		}
 27 		public static Service newInsance(String name){
 28 			Provider provider= providers.get(name);
 29 			if(provider==null){
 30 				throw new IllegalArgumentException("No provider registered with name:"+ name);
 31 			}
 32 			return provider.newService();
 33 		}
 34 	}
 35