装饰模式

• Decorator
• 持有被装饰实例，实现同一接口

• public interface Sourceable {
      public void method();
  }
  public class Source implements Sourceable {
      @Override
      public void method(){}
  }
  public class Decorator implements Sourceable {
      private Sourceable source;
      public Decorator(Sourceable source) {
          super();
          this.source = source;
      }
      @Override
      public void method() {
          source.method();
      }
  }