code: @SuppressWarnings("unchecked")
  	public <T> T get(String fieldName) throws BeanException{
  		if(Map.class.isAssignableFrom(beanClass)){
  			return (T) ((Map<?, ?>)bean).get(fieldName);
  		}else{
  			try {
  				final Method method = BeanUtil.getBeanDesc(beanClass).getGetter(fieldName);
  				if(null == method){
  					throw new BeanException("No get method for {}", fieldName);
  				}
  				return (T) method.invoke(this.bean);
  			} catch (Exception e) {
  				throw new BeanException(e);
  			}
  		}
  	}
docs: 获得字段对应值
  @param <T> 属性值类型
  @param fieldName 字段名
  @return 字段值
  @throws BeanException 反射获取属性值或字段值导致的异常