code: @SuppressWarnings("deprecation")
  	protected Object createObject(Class<?> targetClass) throws ReflectiveOperationException {
  		Enhance en = targetClass.getAnnotation(Enhance.class);
  		boolean enhance = (en != null ? en.value() : this.enhance);
  		
  		return enhance ? com.jfinal.aop.Enhancer.enhance(targetClass) : targetClass.newInstance();
  	}
docs: 由于上层已经处理过 singleton，所以 Enhancer.enhance() 方法中不必关心 singleton