docs: @Override
  	public void afterPropertiesSet() throws NoSuchBeanDefinitionException, NoUniqueBeanDefinitionException,
  			SecurityException, NoSuchFieldException
  	{
  		// 如果未指定groupTemplate，取上下文中唯一的GroupTemplate对象
  		if (config == null)
  		{
  			config = getApplicationContext().getBean(BeetlGroupUtilConfiguration.class);
  			this.groupTemplate = config.getGroupTemplate();
  		}
  
  		// 如果没有设置ContentType，设置个默认的
  		if (getContentType() == null)
  		{
  			String charset = groupTemplate.getConf().getCharset();
  			setContentType("text/html;charset=" + charset);
  		}
  
  	}