code: public void close() {
  		IoUtil.close(this.channel);
  
  		if (null != this.group && false == this.group.isShutdown()) {
  			try {
  				this.group.shutdownNow();
  			} catch (IOException e) {
  				// ignore
  			}
  		}
  
  		// 结束阻塞
  		synchronized (this) {
  			this.notify();
  		}
  	}
docs: 关闭服务